fix: allow for empty groupId in form (#7798) (#7802)

`groupId` parameter because of the change in validation wasn't parsed
correctly. Intent was to fill it when it is empty, when the form is
loaded. By mistake the same logic applies when you manually remove all
characters from the text field.

<!-- Thanks for creating a PR! To make it easier for reviewers and
everyone else to understand what your changes relate to, please add some
relevant content to the headings below. Feel free to ignore or delete
sections that you don't think are relevant. Thank you! ❤️ -->

## About the changes
<!-- Describe the changes introduced. What are they and why are they
being introduced? Feel free to also add screenshots or steps to view the
changes if they're visual. -->

<!-- Does it close an issue? Multiple? -->
Closes #

<!-- (For internal contributors): Does it relate to an issue on public
roadmap? -->
<!--
Relates to [roadmap](https://github.com/orgs/Unleash/projects/10) item:
#
-->

### Important files
<!-- PRs can contain a lot of changes, but not all changes are equally
important. Where should a reviewer start looking to get an overview of
the changes? Are any files particularly important? -->


## Discussion points
<!-- Anything about the PR you'd like to discuss before it gets merged?
Got any questions or doubts? -->

Co-authored-by: Tymoteusz Czech <[email protected]>

frontend/src/component/feature/StrategyTypes/FlexibleStrategy/FlexibleStrategy.tsx

@@ -1,4 +1,4 @@
-import { useMemo } from 'react';
+import { useEffect, useMemo } from 'react';
 import { Box, styled } from '@mui/material';
 import type { IFeatureStrategyParameters } from 'interfaces/strategy';
 import RolloutSlider from '../RolloutSlider/RolloutSlider';
@@ -82,17 +82,17 @@ const FlexibleStrategy = ({
         return parseParameterString(parameters.stickiness);
     }, [loading, defaultStickiness, parameters.stickiness]);
 
-    const groupId = useMemo(() => {
+    useEffect(() => {
         if (!parameters.groupId && !loading) {
             if (isDefaultStrategyEdit || !featureId) {
                 updateParameter('groupId', '');
             } else {
                 updateParameter('groupId', featureId);
             }
         }
+    }, [isDefaultStrategyEdit, featureId, loading]);
 
-        return parseParameterString(parameters.groupId);
-    }, [parameters.groupId, isDefaultStrategyEdit, featureId, loading]);
+    const groupId = parseParameterString(parameters.groupId);
 
     if (loading) {
         return <Loader />;
@@ -126,7 +126,10 @@ const FlexibleStrategy = ({
                         value={groupId}
                         disabled={!editable}
                         onChange={(e) =>
-                            updateParameter('groupId', e.target.value)
+                            updateParameter(
+                                'groupId',
+                                parseParameterString(e.target.value),
+                            )
                         }
                         data-testid={FLEXIBLE_STRATEGY_GROUP_ID}
                         error={Boolean(errors?.getFormError('groupId'))}