perf: Use Caching in Priority Nonce Mempool for Tx Look ups (backport #520)

[mergify]

Before Optimization:

After Optimization:

---

This is an automatic backport of pull request #520 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 3376dd3 has failed:

On branch mergify/bp/release/v2.x.x/pr-520
Your branch is up to date with 'origin/release/v2.x.x'.

You are currently cherry-picking commit 3376dd3.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   block/base/lane.go
	modified:   block/base/mempool.go
	modified:   block/base/options.go
	modified:   block/base/priority_nonce.go
	modified:   lanes/base/mempool_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   block/base/mempool_test.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[codecov]

Codecov Report

Attention: Patch coverage is 7.14286% with 13 lines in your changes missing coverage. Please review.

Please upload report for BASE (release/v2.x.x@72a11dc). Learn more about missing BASE report.

Files	Patch %	Lines
block/base/priority_nonce.go	0.00%	11 Missing ⚠️
block/base/mempool.go	33.33%	2 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                @@
##             release/v2.x.x     #524   +/-   ##
=================================================
  Coverage                  ?   49.10%           
=================================================
  Files                     ?       39           
  Lines                     ?     1682           
  Branches                  ?        0           
=================================================
  Hits                      ?      826           
  Misses                    ?      766           
  Partials                  ?       90           

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