Remove PromMetrics proxy, check for promMetrics with isPromAvailable()

[busma13]

This is a follow-up PR to #3629 which created a utility function to test if promMetrics are available, allowing assets to be backward compatible with teraslice before promMetrics were introduced (< 1.4.0). At the same time we decided to just make isPromAvailable() checks everywhere promMetrics was used, instead of using a proxy to catch calls to undefined functions. See #3625 for more details.

This PR makes the following changes:

• Removes the promMetricsAPI Proxy from terafoundation
• Add checks using isPromAvailable before all calls to promMetricsAPI functions.
• Update promMetrics docs.
• Bump teraslice from 1.7.1 to 1.7.2
• Bump job-components from 0.75.0 to 0.75.1
• Bump terafoundation from 0.64.0 to 0.64.1