WebSearch: webcoll performance improvements

• Introduces new -q/--quick CLI argument that improves webcoll performance by skipping the rebuilding of webpage cache for collections whose reclist has not been modified within the last phase1 run (unless --force or --collection CLI arguments were specified).

• Removes a point of sleep that could have lead to potential race conditions.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>