fix calling SoundTriggerMiddleware in safeMode

deleteSoundModel is calling into the SoundTriggerModdleware when safe
mode is enabled. Middleware should not be called in this case.

Bug: 152354427
Test: atest SoundTriggerServiceTest#testServiceDisabledInSafeMode
Change-Id: I1fa13fd32a384b59928a5deb9505dc4a1e757efa