WiredTiger has some specific code base that gets executed only for standalone or non-standalone mode builds. Most of the evergreen tests run in both standalone and non standalone modes.

None of the non standalone build tests run as part of the PR testing. Due to this reason, any specific change that is related to the non standalone mode is not tested until it is merged.

For example, the code change of WT-10949 was added and reverted due to this reason. By adding non standalone mode tests to the PR testing can solve to avoid unnecessary reverts due to failure in non standalone part of the codebase.