"full builds of benchmark" message should include profile

[jyn514]

rust-lang/rust#88679 (comment) says "Very large regression in instruction counts (up to 6.6% on full builds of regression-31157)". But the actual regressed build is "regression-31157-doc".

[jyn514]

This came up again in today's compiler triage meeting: https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202021-11-24.20.2354818/near/262609391