Make $card-border-radius default to $border-radius
Make $card-border-radius default to $border-radius

They already share the same value (`.25rem`)
Refs #17597
[skip sauce]
9-chirno/chirno,lipis/bootstrap,IdanCo/bootstrap,TheFridayInstitute/bootstrap,bardiharborow/bootstrap,Lyricalz/bootstrap,copperdesign/bootstrap,nice-fungal/bootstrap,xt0rted/bootstrap,gijsbotje/bootstrap,lemuelbarango/bootstrap,Hemphill/bootstrap-docs,copperdesign/bootstrap,david-schopf/bootstrap,bootstrapbrasil/bootstrap,vsn4ik/bootstrap,Delagen/bootstrap,johnajacob/bootstrap,bardiharborow/bootstrap,Lyricalz/bootstrap,afuno/bootstrap,blockstack/blockstack-bootstrap,frostbitten/bootstrap,fschumann1211/bootstrap,lemuelbarango/bootstrap,supergibbs/bootstrap,yuyokk/bootstrap,GerHobbelt/bootstrap,NCARB/bootstrap,creativewebjp/bootstrap,tagliala/bootstrap,sealocal/bootstrap,tjkohli/bootstrap,inway/bootstrap,bootstrapbrasil/bootstrap,tibo66/bootstrap,Hemphill/bootstrap-docs,JumpLinkNetwork/bootstrap-backward,bardiharborow/bootstrap,twbs/bootstrap,blockstack/blockstack-bootstrap,SweetProcess/bootstrap,IdanCo/bootstrap,andresgalante/bootstrap,blockstack/blockstack-bootstrap,Hemphill/bootstrap-docs,Scoutski/bootstrap,seanwu99/bootstrap,NCARB/bootstrap,n054/bootstrap,tjkohli/bootstrap,johnajacob/bootstrap,seanwu99/bootstrap,sealocal/bootstrap,n054/bootstrap,afuno/bootstrap,coliff/bootstrap,vsn4ik/bootstrap,janseliger/bootstrap,vsn4ik/bootstrap,seanwu99/bootstrap,joblocal/bootstrap,janseliger/bootstrap,davethegr8/bootstrap,slavanga/bootstrap,realcrowd/bootstrap,Scoutski/bootstrap,tagliala/bootstrap,NCARB/bootstrap,9-chirno/chirno,fschumann1211/bootstrap,realcrowd/bootstrap,mpharrigan/bootstrap,onenameio/rhythm-bootstrap,zalog/bootstrap,slavanga/bootstrap,lemuelbarango/bootstrap,coliff/bootstrap,Hightrack/bootstrap,supergibbs/bootstrap,hellonewman81/bs4,Scoutski/bootstrap,tibo66/bootstrap,abvalentine/bootstrap,Delagen/bootstrap,gijsbotje/bootstrap,jipexu/bootstrap,peterblazejewicz/bootstrap,igoynawamreh/bootstrap,hebbet/bootstrap,copperdesign/bootstrap,hellonewman81/bs4,tibo66/bootstrap,zalog/bootstrap,stanwmusic/bootstrap,tomlutzenberger/bootstrap,urbit/bootstrap,vsn4ik/bootstrap,inway/bootstrap,realcrowd/bootstrap,afuno/bootstrap,hebbet/bootstrap,abvalentine/bootstrap,realcrowd/bootstrap,tibo66/bootstrap,andresgalante/bootstrap,m5o/bootstrap,9-chirno/chirno,stanwmusic/bootstrap,creativewebjp/bootstrap,andresgalante/bootstrap,twbs/bootstrap,edanbarak/bootstrap,n054/bootstrap,afuno/bootstrap,Lyricalz/bootstrap,nice-fungal/bootstrap,yuyokk/bootstrap,kvlsrg/bootstrap,n054/bootstrap,yuyokk/bootstrap,TheFridayInstitute/bootstrap,hebbet/bootstrap,igoynawamreh/bootstrap,hellonewman81/bs4,nice-fungal/bootstrap,joblocal/bootstrap,Delagen/bootstrap,johnajacob/bootstrap,supergibbs/bootstrap,supergibbs/bootstrap,sealocal/bootstrap,onenameio/rhythm-bootstrap,lipis/bootstrap,peterblazejewicz/bootstrap,jipexu/bootstrap,JumpLinkNetwork/bootstrap-backward,edanbarak/bootstrap,tomlutzenberger/bootstrap,creativewebjp/bootstrap,stanwmusic/bootstrap,wesamco/bootstrap-rtl,igoynawamreh/bootstrap,kvlsrg/bootstrap,zalog/bootstrap,fschumann1211/bootstrap,frostbitten/bootstrap,lemuelbarango/bootstrap,gijsbotje/bootstrap,Lyricalz/bootstrap,m5o/bootstrap,abvalentine/bootstrap,TheFridayInstitute/bootstrap,SweetProcess/bootstrap,kvlsrg/bootstrap,igoynawamreh/bootstrap,johnajacob/bootstrap,SweetProcess/bootstrap,davethegr8/bootstrap,vitaligent/4,TheFridayInstitute/bootstrap,mpharrigan/bootstrap,tomlutzenberger/bootstrap,hebbet/bootstrap,edanbarak/bootstrap,joblocal/bootstrap,xt0rted/bootstrap,IdanCo/bootstrap,peterblazejewicz/bootstrap,mpharrigan/bootstrap,JumpLinkNetwork/bootstrap-backward,frostbitten/bootstrap,david-schopf/bootstrap,IdanCo/bootstrap,Scoutski/bootstrap,stanwmusic/bootstrap,edanbarak/bootstrap,wesamco/bootstrap-rtl,yuyokk/bootstrap,lipis/bootstrap,jipexu/bootstrap,GerHobbelt/bootstrap,vitaligent/4,SweetProcess/bootstrap,sealocal/bootstrap,slavanga/bootstrap,slavanga/bootstrap,seanwu99/bootstrap,Hightrack/bootstrap,vitaligent/4,davethegr8/bootstrap,davethegr8/bootstrap,tagliala/bootstrap,abvalentine/bootstrap,joblocal/bootstrap,janseliger/bootstrap,onenameio/rhythm-bootstrap,Hemphill/bootstrap-docs,copperdesign/bootstrap,wesamco/bootstrap-rtl,jipexu/bootstrap,9-chirno/chirno,xt0rted/bootstrap,JumpLinkNetwork/bootstrap-backward,xt0rted/bootstrap,lipis/bootstrap,janseliger/bootstrap,creativewebjp/bootstrap,fschumann1211/bootstrap,wesamco/bootstrap-rtl,Delagen/bootstrap,urbit/bootstrap,andresgalante/bootstrap,frostbitten/bootstrap,GerHobbelt/bootstrap,Hightrack/bootstrap,inway/bootstrap,bardiharborow/bootstrap,david-schopf/bootstrap,bootstrapbrasil/bootstrap,urbit/bootstrap,gijsbotje/bootstrap,NCARB/bootstrap