chore(global): remove once_cell in favor of the standard library

[llogiq]

Which issue does this PR address?

None, it's just one step to remove the once_cell crate from the build path.

Rationale

Once the other dependencies using it have been updated to use the standard library types instead, the build will require one crate less.

What changed?

This just wholesale removes the once_cell crate from all iggy crate's dependencies, replacing all uses with the respective standard library types.

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

None

[github-actions]

Thanks for the PR. It is labeled S-waiting-on-review and queued for review.

Slash commands (own line, regular comment) move it around the queue:

• /ready - back to S-waiting-on-review after addressing feedback
• /author - flip to S-waiting-on-author while you finish changes
• /request-review @user-or-team - request a reviewer

See CONTRIBUTING.md for details.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.24%. Comparing base (4a48008) to head (06f0942).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3524      +/-   ##
============================================
- Coverage     74.27%   74.24%   -0.03%     
  Complexity      937      937              
============================================
  Files          1259     1259              
  Lines        125969   125969              
  Branches     101644   101688      +44     
============================================
- Hits          93558    93525      -33     
+ Misses        29396    29387       -9     
- Partials       3015     3057      +42     

Components	Coverage Δ
Rust Core	75.16% <ø> (ø)
Java SDK	58.57% <ø> (ø)
C# SDK	71.40% <ø> (-0.71%)	⬇️
Python SDK	88.88% <ø> (ø)
PHP SDK	84.29% <ø> (ø)
Node SDK	91.35% <ø> (+0.12%)	⬆️
Go SDK	40.36% <ø> (ø)

Files with missing lines	Coverage Δ
core/connectors/runtime/src/source.rs	80.11% <ø> (ø)
core/connectors/sdk/src/lib.rs	56.17% <ø> (ø)
core/connectors/sdk/src/sink.rs	75.59% <ø> (ø)
core/connectors/sdk/src/source.rs	80.27% <ø> (ø)
core/server_common/src/memory_pool.rs	70.00% <ø> (ø)

... and 18 files with indirect coverage changes

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