Fix: JobScaler issues that cause request failures

[deanq]

• Integrated asyncio.Queue within JobScaler (removes JobsQueue) and fully take advantage of its blocking .get .put functions
• Using asyncio.Queue(maxsize) to dictate concurrency (via concurrency_modifier)
• JobScaler.set_scale() adjusts concurrency when needed and safe in runtime
• JobScaler.current_occupancy() uses asyncio.Queue size and JobsProgress(set) size to gate capacity
• Simpler/cleaner job acquisition steps
• Removed legacy tracers for http clients
• Run python -m tests.test_serverless.test_modules.run_scale locally to test and benchmark JobScaler features

[gabewillen]

This looks good to me!