chore: change the numConsistent to 2

[c4po]

Change numConsistent from 4 to 2 in eventual consistency check

Description

This PR modifies the numConsistent constant in the eventual consistency check mechanism, reducing it from 4 to 2. This change aims to optimize the consistency check process by requiring fewer consistent reads before considering a resource state as consistent.

Changes

• Updated numConsistent constant in internal/provider/eventual_consistency.go from 4 to 2
• Modified test cases in internal/provider/eventual_consistency_test.go to align with the new numConsistent value

Motivation and Context

• fix issue Occasional timeout when applying the googleworkspace_group_member resource #475
• The previous value of 4 for numConsistent may have been overly conservative, potentially leading to timeouts in resource operations. By reducing this to 2, we aim to strike a better balance between ensuring consistency and avoiding unnecessary timeouts in resource provisioning