Fix AvoidCreate offenses in ee/spec/lib/sidebars

What does this MR do and why?

Related #414635 (closed)

Fix AvoidCreate offenses in ee/spec/lib/sidebars

Small improvement by replacing create with build_stubbed

Finished in 15.16 seconds (files took 11.95 seconds to load)
159 examples, 0 failures

Randomized with seed 14040

[TEST PROF INFO] Time spent in factories: 00:01.701 (9.98% of total time)
[TEST PROF INFO] Factories usage

 Total: 42
 Total top-level: 35
 Total time: 00:01.701 (out of 00:24.061)
 Total uniq factories: 7

   total   top-level     total time      time per call      top-level time               name

      19          19        0.0868s            0.0046s             0.0868s            license
      12          12        0.6117s            0.0510s             0.6117s               user
       3           3        0.1663s            0.0554s             0.1663s              group
       3           0        0.0136s            0.0045s             0.0000s namespace_settings
       3           0        0.0098s            0.0033s             0.0000s namespace_ci_cd_settings
       1           1        0.8369s            0.8369s             0.8369s            project
       1           0        0.0380s            0.0380s             0.0000s          namespace

After

Finished in 14.66 seconds (files took 12.51 seconds to load)
159 examples, 0 failures

Randomized with seed 11034

[TEST PROF INFO] Time spent in factories: 00:01.510 (9.01% of total time)
[TEST PROF INFO] Factories usage

 Total: 36
 Total top-level: 29
 Total time: 00:01.510 (out of 00:23.522)
 Total uniq factories: 7

   total   top-level     total time      time per call      top-level time               name

      19          19        0.0851s            0.0045s             0.0851s            license
       6           6        0.4522s            0.0754s             0.4522s               user
       3           3        0.1853s            0.0618s             0.1853s              group
       3           0        0.0122s            0.0041s             0.0000s namespace_settings
       3           0        0.0083s            0.0028s             0.0000s namespace_ci_cd_settings
       1           1        0.7883s            0.7883s             0.7883s            project
       1           0        0.0388s            0.0388s             0.0000s          namespace

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