Disable queryset caching by default

[jeremystretch]

Proposed Changes

Change the default CACHE_TIMEOUT setting from 900 seconds to zero, effectively disabling caching. This will have no effect on NetBox deployments with CACHE_TIMEOUT defined in configuration.py.

Justification

Queryset caching is being removed in NetBox v3.0 (see #6639) due to frequent issues with cache invalidation. There's really no reason to keep it enabled by default for new deployments.