rust: make sure getScratchPath format has %s
rust: make sure getScratchPath format has %s

Summary:
BuildTargets.getScratchPath's format parameter is supposed
to contain a %s to include the target name, so make sure we supply
one.

Test Plan: CI

Reviewed By: sdwilsh, yiding

fbshipit-source-id: 4650250

nguyentruongtho/buck,rmaz/buck,darkforestzero/buck,facebook/buck,LegNeato/buck,Addepar/buck,Addepar/buck,dsyang/buck,dsyang/buck,zpao/buck,marcinkwiatkowski/buck,shs96c/buck,shybovycha/buck,SeleniumHQ/buck,dsyang/buck,grumpyjames/buck,LegNeato/buck,clonetwin26/buck,k21/buck,shs96c/buck,robbertvanginkel/buck,shybovycha/buck,vschs007/buck,k21/buck,marcinkwiatkowski/buck,darkforestzero/buck,shs96c/buck,clonetwin26/buck,brettwooldridge/buck,sdwilsh/buck,clonetwin26/buck,k21/buck,brettwooldridge/buck,vschs007/buck,daedric/buck,brettwooldridge/buck,davido/buck,kageiit/buck,marcinkwiatkowski/buck,zpao/buck,brettwooldridge/buck,shs96c/buck,JoelMarcey/buck,dsyang/buck,marcinkwiatkowski/buck,ilya-klyuchnikov/buck,zhan-xiong/buck,facebook/buck,shs96c/buck,daedric/buck,shs96c/buck,daedric/buck,LegNeato/buck,rmaz/buck,shybovycha/buck,shs96c/buck,grumpyjames/buck,ilya-klyuchnikov/buck,robbertvanginkel/buck,LegNeato/buck,ilya-klyuchnikov/buck,k21/buck,JoelMarcey/buck,facebook/buck,shybovycha/buck,JoelMarcey/buck,nguyentruongtho/buck,JoelMarcey/buck,daedric/buck,dsyang/buck,marcinkwiatkowski/buck,LegNeato/buck,vschs007/buck,darkforestzero/buck,brettwooldridge/buck,dsyang/buck,rmaz/buck,ilya-klyuchnikov/buck,nguyentruongtho/buck,darkforestzero/buck,ilya-klyuchnikov/buck,sdwilsh/buck,zhan-xiong/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,rmaz/buck,rmaz/buck,JoelMarcey/buck,grumpyjames/buck,daedric/buck,clonetwin26/buck,shybovycha/buck,SeleniumHQ/buck,LegNeato/buck,Addepar/buck,shybovycha/buck,clonetwin26/buck,zhan-xiong/buck,sdwilsh/buck,SeleniumHQ/buck,justinmuller/buck,davido/buck,dsyang/buck,vschs007/buck,clonetwin26/buck,zpao/buck,zpao/buck,daedric/buck,darkforestzero/buck,daedric/buck,zhan-xiong/buck,vschs007/buck,shs96c/buck,zhan-xiong/buck,LegNeato/buck,zhan-xiong/buck,shs96c/buck,vschs007/buck,SeleniumHQ/buck,vschs007/buck,daedric/buck,sdwilsh/buck,sdwilsh/buck,davido/buck,shs96c/buck,zpao/buck,darkforestzero/buck,daedric/buck,Addepar/buck,davido/buck,romanoid/buck,SeleniumHQ/buck,Addepar/buck,justinmuller/buck,marcinkwiatkowski/buck,justinmuller/buck,davido/buck,rmaz/buck,grumpyjames/buck,SeleniumHQ/buck,shybovycha/buck,rmaz/buck,justinmuller/buck,robbertvanginkel/buck,darkforestzero/buck,dsyang/buck,marcinkwiatkowski/buck,vschs007/buck,kageiit/buck,clonetwin26/buck,darkforestzero/buck,grumpyjames/buck,ilya-klyuchnikov/buck,rmaz/buck,romanoid/buck,sdwilsh/buck,robbertvanginkel/buck,Addepar/buck,k21/buck,davido/buck,SeleniumHQ/buck,davido/buck,dsyang/buck,grumpyjames/buck,shybovycha/buck,davido/buck,k21/buck,LegNeato/buck,grumpyjames/buck,ilya-klyuchnikov/buck,zhan-xiong/buck,shybovycha/buck,LegNeato/buck,zhan-xiong/buck,Addepar/buck,rmaz/buck,k21/buck,rmaz/buck,vschs007/buck,kageiit/buck,JoelMarcey/buck,justinmuller/buck,clonetwin26/buck,JoelMarcey/buck,nguyentruongtho/buck,k21/buck,robbertvanginkel/buck,nguyentruongtho/buck,shybovycha/buck,vschs007/buck,rmaz/buck,darkforestzero/buck,davido/buck,zpao/buck,darkforestzero/buck,nguyentruongtho/buck,dsyang/buck,SeleniumHQ/buck,robbertvanginkel/buck,facebook/buck,marcinkwiatkowski/buck,robbertvanginkel/buck,darkforestzero/buck,davido/buck,clonetwin26/buck,Addepar/buck,SeleniumHQ/buck,robbertvanginkel/buck,darkforestzero/buck,Addepar/buck,robbertvanginkel/buck,LegNeato/buck,zhan-xiong/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,LegNeato/buck,romanoid/buck,darkforestzero/buck,rmaz/buck,daedric/buck,sdwilsh/buck,SeleniumHQ/buck,k21/buck,brettwooldridge/buck,romanoid/buck,Addepar/buck,SeleniumHQ/buck,justinmuller/buck,brettwooldridge/buck,marcinkwiatkowski/buck,romanoid/buck,justinmuller/buck,shybovycha/buck,davido/buck,zhan-xiong/buck,kageiit/buck,k21/buck,k21/buck,Addepar/buck,robbertvanginkel/buck,vschs007/buck,daedric/buck,kageiit/buck,marcinkwiatkowski/buck,justinmuller/buck,vschs007/buck,sdwilsh/buck,Addepar/buck,dsyang/buck,romanoid/buck,justinmuller/buck,marcinkwiatkowski/buck,sdwilsh/buck,LegNeato/buck,brettwooldridge/buck,shs96c/buck,romanoid/buck,brettwooldridge/buck,justinmuller/buck,sdwilsh/buck,sdwilsh/buck,sdwilsh/buck,facebook/buck,JoelMarcey/buck,nguyentruongtho/buck,shs96c/buck,zhan-xiong/buck,romanoid/buck,romanoid/buck,robbertvanginkel/buck,dsyang/buck,romanoid/buck,clonetwin26/buck,grumpyjames/buck,romanoid/buck,k21/buck,ilya-klyuchnikov/buck,clonetwin26/buck,grumpyjames/buck,daedric/buck,kageiit/buck,justinmuller/buck,daedric/buck,grumpyjames/buck,davido/buck,zhan-xiong/buck,grumpyjames/buck,zpao/buck,LegNeato/buck,ilya-klyuchnikov/buck,romanoid/buck,justinmuller/buck,JoelMarcey/buck,dsyang/buck,rmaz/buck,brettwooldridge/buck,JoelMarcey/buck,k21/buck,justinmuller/buck,davido/buck,Addepar/buck,ilya-klyuchnikov/buck,shybovycha/buck,sdwilsh/buck,shybovycha/buck,JoelMarcey/buck,facebook/buck,marcinkwiatkowski/buck,robbertvanginkel/buck,vschs007/buck,grumpyjames/buck,facebook/buck,brettwooldridge/buck,kageiit/buck,ilya-klyuchnikov/buck,SeleniumHQ/buck,clonetwin26/buck,zhan-xiong/buck,romanoid/buck,JoelMarcey/buck,robbertvanginkel/buck,marcinkwiatkowski/buck,shs96c/buck,clonetwin26/buck,SeleniumHQ/buck,JoelMarcey/buck