fix flakes in test_pods_monitored

[gaelgatelement]

I expect :

  Extra items in the left set:
  'pytest-sr25rymj-synapse-fed-reader-8467697d74-rq5rz'
  'pytest-sr25rymj-haproxy-54cf68977-ghjwf'
  'pytest-sr25rymj-haproxy-54cf68977-ckdz7'
  'pytest-sr25rymj-synapse-main-0'
  'pytest-sr25rymj-postgres-0'
  
  Full diff:
  - set()
  + {
  +     'pytest-sr25rymj-haproxy-54cf68977-ckdz7',
  +     'pytest-sr25rymj-haproxy-54cf68977-ghjwf',
  +     'pytest-sr25rymj-postgres-0',
  +     'pytest-sr25rymj-synapse-fed-reader-8467697d74-rq5rz',
  +     'pytest-sr25rymj-synapse-main-0',
  + }

To be a similar problem to #627

[github-actions]

dyff of changes in rendered templates of CI manifests

No changes in rendered templates

[gaelgatelement]

After discussing, it's not the same issue. Let's figure it out later.