fix clean bpf_map twice in test

[LiZhenCheng9527]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Because cleanup bpf map in loader.Stop(). so there is no need to execute bpf.cleanup again
Which issue(s) this PR fixes:
Fixes #844

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 52.63%. Comparing base (62b5061) to head (8105676).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/bpf/bpf.go	0.00%	3 Missing ⚠️

Files with missing lines	Coverage Δ
pkg/status/status_server.go	33.18% <100.00%> (ø)
pkg/utils/test/bpf_map.go	42.10% <ø> (-1.49%)	⬇️
pkg/bpf/bpf.go	41.07% <0.00%> (-0.75%)	⬇️

... and 2 files with indirect coverage changes

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[hzxuzhonghu]

/lgtm

[kmesh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hzxuzhonghu

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