MINOR: [C++] Remove unnecessary code in MultipathLevelBuilder::Write

[js8544]

The PathBuilder run is unnecessary as MultipathLevelBuilder::Make on line 896 does the visitation already.

[vibhatha]

The CI failure is resolved in #33651

[pitrou]

@js8544 Can you rebase or merge from master to get CI fixes?

[js8544]

@js8544 Can you rebase or merge from master to get CI fixes?

Yep. It's green now.

[ursabot]

Benchmark runs are scheduled for baseline = 1a82720 and contender = c525b57. c525b57 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Failed ⬇️0.39% ⬆️0.12%] test-mac-arm
[Finished ⬇️0.0% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.37% ⬆️0.34%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] c525b572 ec2-t3-xlarge-us-east-2
[Failed] c525b572 test-mac-arm
[Finished] c525b572 ursa-i9-9960x
[Finished] c525b572 ursa-thinkcentre-m75q
[Finished] 1a827200 ec2-t3-xlarge-us-east-2
[Failed] 1a827200 test-mac-arm
[Finished] 1a827200 ursa-i9-9960x
[Finished] 1a827200 ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

[ursabot]

['Python', 'R'] benchmarks have high level of regressions.
test-mac-arm