fix: CompareIpByte skips invalid IP bytes instead of using zero-value IP

[bhumikadangayach]

Fixes #1908

CompareIpByte logged an error on invalid IP bytes but didn't stop - the zero-value IP's String() ("invalid IP") was used as a map key anyway, so multiple malformed entries would collide under the same key, and a malformed entry in one side could incorrectly match against one left over from the other side.

Added continue after the error log in both loops, so malformed entries are skipped entirely instead of participating in the comparison.

Added a test case covering malformed entries mixed with valid ones on both sides, verifying the diff result only reflects genuine IP comparisons.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.59%. Comparing base (32fe3df) to head (21ceff1).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Coverage Δ
pkg/nets/nets.go	45.45% <100.00%> (+4.71%)	⬆️

... and 1 file with indirect coverage changes

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[yashisrani]

There is one commit incorrectly signed off. This means that the author of this commit failed to include a Signed-off-by line in the commit message.

To avoid having PRs blocked in the future, always include Signed-off-by: Author Name authoremail@example.com in every commit message. You can also do this automatically by using the -s flag (i.e., git commit -s).

Here is how to fix the problem so that this code can be merge

[bhumikadangayach]

E2E istio 1.26 failed on the log-collection step after all tests passed - PASS on TestKmeshRestart etc, but exits 1 because of cat: kmesh_daemon.log: No such file or directory afterward. Same pattern on #1845 and #1881, both resolved on re-run. Filed separately as #1911. Could you trigger a re-run?