FIX: Tasks on MacOS agents not completing but marked as succeeded.

[sahilbhattMS]

Description:
Some pipelines using MacOS agents reported tasks not completing but still being marked as succeeded. Disabling resource utilization warnings seemed to mitigate this issue.

An analysis of various debug logs indicated that the problem was due to the resource utilization warnings' implementation in MacOS, where multiple CPU and memory info processes were being invoked simultaneously.

Changes made:

1. Locks added to ensure that there are no simultaneous calls to CPU and memory info processes.
2. Dispose standard output/error streams. Refer: Process class leaks pipes on MacOS when redirecting stdout and stderr dotnet/runtime#58872

Validations done:
The issue did not reproduce on running a test pipeline on a self-hosted MacOS agent using the above-mentioned changes.