Add OpenTelemetry operation count metrics for all Azure Storage operations

[Copilot]

Type of Change

• New feature

Description

• Feature / Bug Fix: Added operation count tracking via OpenTelemetry for all Azure Storage REST API calls to enable monitoring of operation distribution, performance analysis, and cost tracking.

Implementation

Added RecordOperation() calls to 30+ operations across the azstorage component:

High-level operations (azstorage.go):

• Directory: CreateDir, DeleteDir, RenameDir, ReadDir, StreamDir
• File: CreateFile, OpenFile, DeleteFile, RenameFile
• I/O: ReadFile, ReadInBuffer, WriteFile, CopyToFile, CopyFromFile
• Metadata: GetAttr (GetProperties), Chmod, Chown
• Advanced: TruncateFile, FlushFile, GetFileBlockOffsets
• Blocks: StageData, CommitData, GetCommittedBlockList
• Symlinks: CreateLink, ReadLink

Low-level operations (block_blob.go):

• List, StageBlock, CommitBlocks, GetCommittedBlockList

Metric exported:

blobfuse_operations_total{operation, component}

Example queries:

# Top operations
topk(10, sum(rate(blobfuse_operations_total[5m])) by (operation))

# Read vs write ratio
sum(rate(blobfuse_operations_total{operation=~"Read.*|GetAttr"}[5m])) /
sum(rate(blobfuse_operations_total{operation=~"Write.*|Create.*"}[5m]))

# Block operations rate
sum(rate(blobfuse_operations_total{operation=~".*Block.*|Stage.*|Commit.*"}[5m]))

Documentation updates:

• Added operation metrics section to doc/metrics.md
• Included Prometheus queries for operation analysis
• Added alerting examples for unusual patterns

How Has This Been Tested?

• Component builds successfully with go build -tags=unittest ./component/azstorage/...
• All existing tests pass
• Metrics integration follows existing patterns from cache and Azure request metrics

Checklist

• The purpose of this PR is explained in this or a referenced issue.
• Tests are included and/or updated for code changes.
• Documentation update required.
• Updates to module CHANGELOG.md are included.
• License headers are included in each file.

Related Links

• Builds on existing OpenTelemetry metrics infrastructure from previous PRs
• Complements Azure Storage request/response/error metrics already in place

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