Update logic to use ClearGrShaderDiskCacheOnInvalidPrefix.

Update logic to use ClearGrShaderDiskCacheOnInvalidPrefix to balance
control and enabled group sample counts.
This feature flag check was inside an if condition which was causing
enable and control group sample count to be different.
Move the flag ClearGrShaderDiskCacheOnInvalidPrefix check outside of if
condition.

Bug: 348707692
Change-Id: I06ae7cf01649bf308e9053736df2e4cc0691d5c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5696566
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: vikas soni <vikassoni@chromium.org>
Auto-Submit: vikas soni <vikassoni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1326300}