Item not getting compressed even though memory compression is enabled

Found issue on 7.1.0-1885

Steps to reproduce:

1. Create a cluster with 2 KV, 1 Inde and 1 n1ql
2. Create 2 Buckets, 2 Scopes and 2 Collections
3. Create 1 gsi for each collection
4. Perform delete operation.
5. Wait for sleep interval
6. Verify using stat - 'merges' > 0, as pages should merge after delete
7. Perform CRUD operation with 20% delete, 1000% add, 20% update ( Raise from 50K items to 5M)
8. Check for num_compressed count > 0

Issue: num_rec_compressed count is zero for most of the indexes though num_rec_compressible count is > 0. 

Attaching server side logs:
https://cb-engineering.s3.amazonaws.com/Zero_Compressed_item_count_issue/collectinfo-2021-12-13T173647-ns_1%40172.23.121.46.zip
https://cb-engineering.s3.amazonaws.com/Zero_Compressed_item_count_issue/collectinfo-2021-12-13T173647-ns_1%40172.23.121.47.zip
https://cb-engineering.s3.amazonaws.com/Zero_Compressed_item_count_issue/collectinfo-2021-12-13T173647-ns_1%40172.23.121.60.zip
https://cb-engineering.s3.amazonaws.com/Zero_Compressed_item_count_issue/collectinfo-2021-12-13T173647-ns_1%40172.23.121.62.zip