Merge branch '21.3-ATLASSIM-3903' into '21.3'

SCT RDO updates to reduce size for overlay MC (ATLASSIM-3903)

See merge request atlas/athena!20374

(cherry picked from commit e0854f09)

007a644d Create SCT3_RawData_p4
3590a454 Create SCT3_RawData_p4
6d958f55 Store row number (3 bits) and strip number (13 bits) instead of Identifier (64 bits)
fe329d46 Bug fixes
a2642511 Add comments
a16b4d8a Code cleanup
8425f003 Comment out unused variable
fd2cdecf Use unique_ptr
0434a27d Use unique_ptr
1d1963a4 Code cleanup