## Describe your changes
`NB_LAZY_CONN_INACTIVITY_THRESHOLD` was parsed with `strconv.Atoi`, i.e.
as a bare
integer number of minutes. The documentation, however, states it takes a
Go duration
(e.g. `30m`, `1h`). As a result any documented value such as `30m` or
`5m` failed to
parse and **silently fell back to the 15m default**, so the setting
appeared to have
no effect.
`inactivityThresholdEnv()` now parses the value with
`time.ParseDuration`, matching
the docs. A bare integer is still accepted as a number of minutes for
backwards
compatibility, and an unparseable value logs a warning and falls back to
the default.
Added `TestInactivityThresholdEnv` covering Go-duration values
(`30m`/`1h`/`90s`), the
bare-integer minutes fallback, and zero/negative/garbage inputs.
## Issue ticket number and link
N/A