fix #2602

[amusso01]

Description

Correct the opacity of the loader of the dialog box to display it on loading

Issues

• Fix Loading spinner on import of local vector #2602
• ...

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x", remove the others)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior? (You can also link to an open issue here)
While uploading local vector loader doesn't appear

What is the new behavior?
Loader appear inside the dialog box while uploading local vector

Does this PR introduce a breaking change? (check one with "x", remove the other)

• Yes
• No

[coveralls]

Coverage increased (+0.006%) to 80.367% when pulling 923c28a on amusso01:working into 5fe67f5 on geosolutions-it:master.

[offtherailz]

Most probably the spinner is a component from react spinkit.
see here how to disable spinner initial animation.
You should use it instead of overriding css or you risk disable all the animations for the spinners.
A test in this case should be applied to the specific component instead of the generic dialog.