roachtest: add test for admission control disk bandwidth

[aadityasondhi]

This test runs a single node target cluster that has two workloads running on it. The lower priority (qos=background) is very bandwidth intensive, and without the AC bandwidth limiter would saturate the provisioned bandwidth (controlled using cgroups).

This test shows how setting the cluster setting kvadmission.store.provisioned-bandwidth limits the disk bandwidth usage of lower priority work and shapes it at the value set in the setting.

Fixes https://github.com/cockroachdb/cockroach/issues/121576.

Release note: None

[cockroach-teamcity]

This change is 

[aadityasondhi]

Link to grafana dashboard showing this.

Note: I manually adjusted setting in that run to show how the shaping is working. In this test, we set those limits right away and assert on never going too far past the provisioned limit.

[craig[bot]]

Build succeeded:

• linux_arm64_build
• macos_amd64_build
• acceptance
• docker_image_amd64
• unit_tests
• linux_amd64_build
• local_roachtest
• lint
• linux_amd64_fips_build
• local_roachtest_fips
• examples_orms
• windows_build
• check_generated_code
• macos_arm64_build