test: delete sliceopt.go
test: delete sliceopt.go

It tests the behavior of the old deleted compiler.

Fixes #17362.

Change-Id: Ia2fdec734c5cbe724a9de562ed71598f67244ab3
Reviewed-on: https://go-review.googlesource.com/30593
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

nawawi/go,momchil-velikov/go,josharian/go,derekmarcotte/go,momchil-velikov/go,nawawi/go,Cofyc/go,CAFxX/go,golang/go,vsekhar/elastic-go,CAFxX/go,goodlang/good,ImJasonH/go,polyverse-security/go,akutz/go,ImJasonH/go,josharian/go,codestation/go,goodlang/good,Cofyc/go,derekmarcotte/go,suncycheng/go,vsekhar/elastic-go,golang/go,polyverse-security/go,CAFxX/go,josharian/go,akutz/go,vsekhar/elastic-go,linux-on-ibm-z/go,linux-on-ibm-z/go,Cofyc/go,cloudflare/go,ImJasonH/go,josharian/go,momchil-velikov/go,codestation/go,christopher-henderson/Go,momchil-velikov/go,derekmarcotte/go,cloudflare/go,golang/go,nawawi/go,codestation/go,akutz/go,josharian/go,polyverse-security/go,CAFxX/go,golang/go,goodlang/good,nawawi/go,josharian/go,codestation/go,CAFxX/go,goodlang/good,CAFxX/go,suncycheng/go,derekmarcotte/go,momchil-velikov/go,vsekhar/elastic-go,cloudflare/go,ImJasonH/go,polyverse-security/go,codestation/go,suncycheng/go,cloudflare/go,derekmarcotte/go,derekmarcotte/go,linux-on-ibm-z/go,cloudflare/go,vsekhar/elastic-go,CAFxX/go,ImJasonH/go,cloudflare/go,goodlang/good,golang/go,golang/go,linux-on-ibm-z/go,linux-on-ibm-z/go,codestation/go,golang/go,goodlang/good,nawawi/go,derekmarcotte/go,cloudflare/go,akutz/go,linux-on-ibm-z/go,suncycheng/go,akutz/go,polyverse-security/go,goodlang/good,linux-on-ibm-z/go,nawawi/go,CAFxX/go,polyverse-security/go,Cofyc/go,ImJasonH/go,akutz/go,Cofyc/go,Cofyc/go,momchil-velikov/go,ImJasonH/go,Cofyc/go,akutz/go,codestation/go,nawawi/go,suncycheng/go,Cofyc/go,momchil-velikov/go,suncycheng/go,derekmarcotte/go,linux-on-ibm-z/go,goodlang/good,ImJasonH/go,suncycheng/go,vsekhar/elastic-go,suncycheng/go,polyverse-security/go,vsekhar/elastic-go,akutz/go,josharian/go,codestation/go,vsekhar/elastic-go,golang/go,polyverse-security/go,nawawi/go,cloudflare/go,josharian/go,momchil-velikov/go