If the purpose is to clear out the PDB log ...
============ clear trunc pt, clear log
use primary_db
go
sp_stop_rep_agent primary_db
go
dbcc settrunc(ltm,ignore)
go
dump tran primary_db with truncate_only
go
============ reset RSSD
-- in RSSD
rs_zeroltm <ds>,primary_db
go
============ reset trunc pt
use primary_db
go
dbcc settrunc(ltm,valid)
go
sp_start_rep_agent primary_db
go
============
... then make sure the repagent starts, no RS threads are down, and txns are flowing again.
No need to suspend/resume the PDB->RS connection. (NOTE: If you also have an active DSI connection into the PDB, and you're also replicating these maintuser txns out of the PDB, then suspending/resuming the connection could be performed if you want to ensure inbound/maintuser txns are picked up by the repagent and sent to the RS.)
No need to put the database into single user mode.
Obviously (?) at this point txns should now be flowing again but ... you have a few other issues you need to address ...
1 - Why did the PDB log fill up in the first place? (ie, if the root cause hasn't been addressed then your PDB log could fill up again)
2 - Your RDB is now out of sync with your PDB; and there's a chance some of this out-of-sync-data could cause the DSI (into the RDB) to do down, ymmv.
3 - How you resync your RDB will depend on your RS version (Hint: It's a bit easier to resync RDBs if you're running RS 15.6+.)