Clickhouse SPIFFE MTLs and SQL over HTTPS support

[OGKevin]

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Summary

This merge request addresses a critical ClickHouse URL corruption bug that occurred during connection retries and introduces several improvements to database connection handling, including context support with timeouts.

Bug Fix

• Fixed ClickHouse URL corruption bug that occurred on retry attempts
  • Root cause: connectClickHouse() was mutating the connection struct's driver field
  • Solution: Modified to use local variables instead of modifying the original connection object
  • Before fix: Second connection attempt failed with dial tcp: lookup clickhouse+https: no such host
  • After fix: All connection attempts process URLs correctly
  • Bug affected all ClickHouse connection types (HTTP, HTTPS, TCP)

Connection Handling Improvements

• Added context support throughout the database connection call chain
  • Updated method signatures to accept and propagate context
  • Replaced blocking Ping() calls with context-aware PingContext(ctx)
  • Added configurable timeout support for database operations
  • Default 30-second timeout if not explicitly configured

TLS Configuration Enhancements

• Refactored ClickHouse TLS configuration for better testability and maintainability
  • Created MTLSSetup interface for dependency injection
  • Added TLSConfigResult structure to encapsulate TLS configuration results
  • Extracted TLS configuration logic into configureClickHouseTLS()
  • Unified ClickHouse connection handling in connectClickHouse()

Testing Improvements

• Enhanced test coverage for ClickHouse TLS configuration
  • Added integration tests that use the actual production code path
  • Implemented proper dependency injection with mock objects
  • Created comprehensive test cases for URL parameter handling
  • Removed redundant test (TestURLParameterRemovalUnit)

Compatibility

• Maintains backward compatibility with all existing connection string formats
• Preserves all connection pool settings and StartupSQL execution
• No breaking API changes

Testing

• All tests pass, including the new ClickHouse URL bug reproduction test
• Code compiles successfully with go build .
• All existing functionality remains intact

Configuration Example

Users can now configure timeouts in their job YAML:

jobs:
- name: clickhouse_job
  timeout: 10s  # Custom timeout for database operations
  connections:
    - "clickhouse+http://localhost:9000/default"