Add configuration property to disable long timers in Micrometer Observations

[mhalbritter]

Micrometer Tracing will get a feature to turn off the long task timers in observations. We should add a configuration property for that, too.

[jonatan-ivanov]

Thanks for keeping this in mind. I merged the changes in Micrometer, they are available in the latest snapshot and planned to be released in 1.13.0-M2.