fix: retry cgroup2/bpf-fs path check to handle mount propagation delay

[bhumikadangayach]

Fixes #1842

The kmesh-daemon was crashing on startup with "stat /mnt/kmesh_cgroup2: no such file or directory" when running on kind. Traced it to ParseConfig() in daemon/options/bpf.go doing a single os.Stat call with no retry - if the mount isn't ready yet (which happens on kind due to mount propagation delay), it fails immediately instead of waiting.

This PR adds a waitForPath() helper that retries the stat call up to 10 times with 500ms between attempts (5 seconds total) before giving up. Applied to both the cgroup2 path and bpf-fs path checks.

Verified with make build - compiles clean, no errors.

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[kmesh-bot]

Welcome @bhumikadangayach! It looks like this is your first PR to kmesh-net/kmesh 🎉

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.62%. Comparing base (09e96d3) to head (3284f68).
⚠️ Report is 3 commits behind head on main.
see 1 file with indirect coverage changes

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[LiZhenCheng9527]

Suggested change

	for i := 0; i < maxRetries; i++ {
	for i := 0; i <= maxRetries; i++ {

Ensure that a retry is attempted even after the last failure

[bhumikadangayach]

Fixed, thanks!

[bhumikadangayach]

The failing E2E appears to be TestCrossNamespace, where the unenrolled workload unexpectedly gets L7 processing (X-Request-Id). TestKmeshRestart passes with 360/360 successful requests. This appears unrelated to the cgroup2/bpf-fs retry change.

[bhumikadangayach]

Same failure on the IPv6 run too - TestCrossNamespace, unenrolled workload getting X-Request-Id set. Unrelated to this change, only touches daemon/options/bpf.go.

[bhumikadangayach]

This run hit #1911 - tests all passed (TestCrossNamespace, TestKmeshRestart 350/350), suite still exits 1 on log-collection step. Unrelated to this change.