all.bash: use locally installed version of prettier
all.bash: use locally installed version of prettier

Switching all.bash to use a locally installed version
of prettier to remove the expectation that it is
globally installed.

Change-Id: Ib3bf0da16b3d8bfad817be693fff62776f6e99da
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/313529
Trust: Jamal Carvalho <e0195770807aa8c82b0b128d9c0423b5ad035172@golang.org>
Run-TryBot: Jamal Carvalho <e0195770807aa8c82b0b128d9c0423b5ad035172@golang.org>
Reviewed-by: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
TryBot-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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