Fixing unnessecary and even wrong error log

[steiler]

On the call to MustWait on the dependency manager node, with a given stage, a non existing stage entry triggered an error log. However the non existence must simply be reflected by a false value. No Wait needs to happen.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (49fd647) 53.64% compared to head (3bf8cc1) 53.61%.

❗ Current head 3bf8cc1 differs from pull request most recent head 9f4f08b. Consider uploading reports for the commit 9f4f08b to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1892      +/-   ##
==========================================
- Coverage   53.64%   53.61%   -0.04%     
==========================================
  Files         154      154              
  Lines       11236    11227       -9     
==========================================
- Hits         6028     6019       -9     
  Misses       4347     4347              
  Partials      861      861              

Files	Coverage Δ
clab/dependency_manager/dependency_node.go	95.55% <100.00%> (ø)
clab/clab.go	75.16% <66.66%> (-0.50%)	⬇️