Views Time cache "Never cache" label is misleading and caches permanently

Problem/Motivation

The Time cache plugin offers 0 => 'Never cache' for results_lifespan/output_lifespan, but 0 does not disable caching. getLifespan() returns 0, so Time::cacheSetMaxAge() returns Cache::PERMANENT and the item is stored permanently, dropped only by cache tag invalidation. The lifespan is a max age; 0 means no limit, i.e. the strongest caching, the opposite of what "Never cache" implies.

Steps to reproduce

See tests

Proposed resolution

Relabel 0 from "Never cache" to something accurate (e.g. "Cache until invalidated" / no maximum age), and document that the lifespan is a max age with 0 meaning no limit.

Remaining tasks

Agree wording; patch the option label and docs; add the kernel test.

User interface changes

The "Never cache" option label in the Time cache settings.

API changes

None.

Data model changes

None.