Fix install issue with default hostname commented
Fix install issue with default hostname commented

Update the `grep` filter to anchor at the start of the line
and allow for whitespace characters, in order to correctly
determine the hostname being set if the default is merely
commented out and the custom one added, instead of overridden.

Fixes #6117

Signed-off-by: Christian Witts <54d9443fc0677c5d0e45d3480abd0c71b03493bb@gmail.com>

wy65701436/harbor,steven-zou/harbor,wy65701436/harbor,reasonerjt/harbor,wy65701436/harbor,wy65701436/harbor,steven-zou/harbor,wy65701436/harbor,reasonerjt/harbor,steven-zou/harbor,steven-zou/harbor,reasonerjt/harbor,reasonerjt/harbor,reasonerjt/harbor,wy65701436/harbor,steven-zou/harbor,reasonerjt/harbor,steven-zou/harbor