[DPE-2648] POC Remove shards #818

Job	Run time
Unit tests	2m 42s
Lint	16s
Check libraries	26s
Build charms / Get workflow version / Get workflow version	5s
Build charms / Collect charms	20s
Build charms / Build mongodb charm \| 22.04	2m 30s
Build charms / Build application charm \| 20.04	2m 5s
charm-integration	13m 27s
ha-integration	51m 59s
relation-integration	21m 14s
legacy-integration	4m 6s
tls-integration	27m 8s
backup-integration	1h 0m 52s
metric-integration	18m 54s
	3h 26m 4s

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