[release-1.14] multi-network: fix eastwest gateway endpoint filtering

[istio-testing]

Manual cherrypick required.

#38762 failed to apply on top of branch "release-1.14":

Applying: multi-network: prevent eastwest gateway endpoint filtering
Applying: rel note
Applying: skip check for 500s
Using index info to reconstruct a base tree...
Falling back to patching base and 3-way merge...
CONFLICT (add/add): Merge conflict in tests/integration/security/authorization_test.go
Auto-merging tests/integration/security/authorization_test.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0003 skip check for 500s
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".