[release-1.10] Update protolock

[istio-testing]

Manual cherrypick required.

#1990 failed to apply on top of branch "release-1.10":

Applying: make proto-commit
Using index info to reconstruct a base tree...
M	proto.lock
Falling back to patching base and 3-way merge...
Auto-merging proto.lock
CONFLICT (content): Merge conflict in proto.lock
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 make proto-commit
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".