test: refactor histogram tests to a table-driven layout

[anshika07012]

What

Refactors the sequential log2 bucket math test cases in histogram_test.go into a single, clean table-driven layout.

Why

Fixes #133

How

• Consolidated the 9 original sequential testing paths into a unified TestHistogramTableDriven suite matching the design style found in internal/cli/trace_test.go.
• Leveraged t.Run() and t.Parallel() to handle subtests concurrently and ensure safe iteration isolation.
• Explicitly expanded input parameter boundaries to cover zero/empty inputs, single value allocations, exact log2 bucket edges, one-past-the-bucket edges, and max bucket clamping at bucket 63.
• Maintained all original value calculations, assertions, and downstream component tests (Merge, Reset, etc.) intact to prevent regressions.

Testing

• go build ./... passes

• go test ./... passes

• go vet ./... passes

• golangci-lint run ./... passes

• Tested locally with: go test -v inside internal/collector/aggregator

• N/A — pure docs/refactor

• sudo ./bin/bpf-verify --read 5s confirms 6/6 programs still load

• ./scripts/verify.sh passes (or specific phase: ./scripts/verify.sh quality)

Checklist

• PR title follows Conventional Commits (test(collector): refactor histogram tests to table-driven layout)
• All commits are DCO-signed (git commit -s)
• No unrelated changes pulled in
• Documentation updated where user-visible behavior changed
• Added/updated tests for new code paths
• If a new doctor rule, paired with a chaos scenario in scripts/verify.sh

[github-actions]

🚀 First PR — welcome aboard!

A few things to expect:

1. CI: every PR runs build + race tests + lint + (eventually) the kernel matrix. If something fails, the log will tell you exactly which gate.
2. DCO: every commit needs Signed-off-by: — git commit -s adds it automatically.
3. Conventional Commits: PR titles like feat(doctor): add new rule or fix(bpf): handle X. We squash-merge by default.
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