* fix: forbid reading OSS buckets for a token with only write permissions
We previously enabled write tokens to also find DBRP buckets, in order to allow
the legacy /write (not /api/v2/write) endpoint to read the DBRP mappings and
find the real bucket id to write to.
This had the unintended consequency of allowing tokens with only write permissions
to read data in buckets via the legacy /query (not /api/v2/query) endpoint with
InfluxQL.
This change fixes the behaviour to allow writing to /write with a write-only
token, while forbidding reading from /query.
* fix: nanosecond precision in tests