Merge branch 'bugfix/100lb-online-hist' into '21.1'

bugfixes in the pixel online monitoring targeting next 21.1 release

See merge request atlas/athena!11042

(cherry picked from commit 2900f9fb [formerly 2e7dfbcf449d4c176e795bc9fb2f2e39ce195848])

f0f348d9 fix of whole IBL cluster histograms
369b6e3c bugfixes of per 100lb histograms from P1 and adjustment of titles of per PP0…

Former-commit-id: 458aa1838adfc3257f48e01be9ed98bd492b60e2