internal/frontend: remove use-path-info for searchRequestRedirectPath
internal/frontend: remove use-path-info for searchRequestRedirectPath

This is a step towards removing the use-path-info experiment.

Search requests now always check the paths table to see if a path exists.

For golang/go#39629

Change-Id: I4ab3acbf043abb3db959b02069e1fe52c2ae8dfc
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/255365
Trust: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
Run-TryBot: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
TryBot-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite