New observability alerting UX report microseconds "μs" instead of milliseconds in reason message for APM Transaction Latency threshold

[cyrille-leclerc]

Kibana version:

7.15 BC on ESS

Original install method (e.g. download page, yum, from source, etc.):

Describe the bug:

New observability alerting UX report microseconds "μs" instead of milliseconds in reason message for APM Transaction Latency threshold

Moreover, there is a problem with the units in the flyout with the "actual value" and the "expected value"

Configured threshold is 200ms (screenshot below) but threshold in the reason message of a violation is "200μs".

Actual: "Latency is above 200 μs (current value is 388 ms) for frontend"
Expected: "Latency is above 200 ms (current value is 388 ms) for frontend"

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)