[Common] TPC PID: Cleanup of CCDB accessors

[jezwilkinson]

Updating TPC PID tasks to optimise CCDB access methods:

• Remove separate calls to "CcdbApi::retrieveHeaders()", use new merged calls to retrieveBlob, getSpecific, getForTimeStamp (avoids pinging CCDB multiple times when accessing info from metadata from retrieved objects)
• Use BasicCCDBManager::getCCDBAccessor() instead of separate ccdbApi object for retrieveBlob (avoids initialising a second UserAgent for each process)
• remove unneeded "nullmetadata" object; minor fix to logic for loading information from headers

Depends on AliceO2Group/AliceO2#14709 for updates to CCDB API.

[github-actions]

O2 linter results: ❌ 49 errors, ⚠️ 68 warnings, 🔕 0 disabled

[amaringarcia]

@ddobrigk would it be possible to have a look at/approve this pull request?
Thanks in advance

[github-actions]

This PR has not been updated in the last 30 days. Is it still needed? Unless further action is taken, it will be closed in 5 days.

[jezwilkinson]

@ktf @jgrosseo @ddobrigk Could someone please take a look at this? The fix was requested by Costin some time ago, it would be good if we can get it merged.

[alibuild]

Error while checking build/O2Physics/o2 for 6233bf5 at 2026-02-09 18:15:

No log files found

Full log here.

[vkucera]

@ddobrigk @iarsene @dsekihat This PR has been opened for review for 3 months without a review.