[release-1.22] Add warning log to check NetworkPolicy for 15008 denial

[istio-testing]

Manual cherrypick required.

#1229 failed to apply on top of branch "release-1.22":

Applying: Add warning log to check NetworkPolicy for 15008 denial
Using index info to reconstruct a base tree...
M	src/proxy.rs
M	src/proxy/pool.rs
Falling back to patching base and 3-way merge...
Auto-merging src/proxy/pool.rs
CONFLICT (content): Merge conflict in src/proxy/pool.rs
Auto-merging src/proxy.rs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Add warning log to check NetworkPolicy for 15008 denial
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".

[howardjohn]

#1236