Migrate GURL accessors to Get* variants in //services

See goo.gle/gurl-accessor-migration for details. From the doc:
These are not simple accessors since they perform string allocations.
Sometimes these strings can be big (MBs) and the current naming scheme
frequently leads to people accidentally calling these rather than the
cheap `*_piece` accessors which return `string_view`.

This CL was generated by the following clang tool on Linux:
https://chromium-review.googlesource.com/c/chromium/src/+/6991932

Bug: 448174617
Change-Id: I8827cd96d4900b3210445bc9d60da3b13717785a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7000032
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1523236}