Deprecate Blink.UseCounter.FencedFrames.*

They were introduced when MPArch started supporting FencedFrames.
As there is no specific purpose to collect this page type specific
metrics any more, this CL deprecates them instead of extending
expiry dates.

UKMs will be still recorded as they are still used in some tests
and might be useful to understand basic feature usages.

OBSOLETE_HISTOGRAMS=Blink.UseCounter.FencedFrames variants are deprecated.

Bug: 331208470
Change-Id: I2cf9d18069d788148e9519c5eae38823f9d8385d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5452332
Reviewed-by: Liam Brady <lbrady@google.com>
Commit-Queue: Liam Brady <lbrady@google.com>
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1294001}