fix: number slider + category slider color spec fails (#32935)

Fixes a spec for slider and cateogry widget where it fails when changing
and asserting the background color

/ok-to-test tags="@tag.Slider"<!-- This is an auto-generated comment:
Cypress test results -->
> [!TIP]
> 🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/8873791272>
> Commit: b7111f115b691aeb6e6ccc2eceb30c476b91e3a3
> Cypress dashboard url: <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=8873791272&attempt=1"
target="_blank">Click here!</a>

<!-- end of auto-generated comment: Cypress test results  -->







<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Tests**
- Modified a specific test case to run exclusively, improving focus on
critical functionality during testing.
- **New Features**
- Enhanced color selection capabilities in the property control for a
more intuitive user interface.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Pawan Kumar <pawankumar@Pawans-MacBook-Pro-2.local>

app/client/cypress/e2e/Regression/ClientSide/Widgets/Sliders/CategorySlider_spec.ts

@@ -286,7 +286,10 @@ describe(
         .GetWidgetCSSFrAttribute(locators._sliderThumb, "background-color")
         .then((sliderColor) => {
           agHelper
-            .GetWidgetCSSFrAttribute(propPane._fillColor, "background-color")
+            .GetWidgetCSSFrAttribute(
+              `${propPane._propertyControlSelectedColorButton("fillcolor")}`,
+              "background-color",
+            )
             .then((newColor) => {
               expect(sliderColor).to.eq(newColor);
             });

app/client/cypress/e2e/Regression/ClientSide/Widgets/Sliders/NumberSlider_spec.ts

@@ -377,7 +377,10 @@ describe("Number Slider spec", { tags: ["@tag.Widget", "@tag.Slider"] }, () => {
       .GetWidgetCSSFrAttribute(locators._sliderThumb, "background-color")
       .then((sliderColor) => {
         agHelper
-          .GetWidgetCSSFrAttribute(propPane._fillColor, "background-color")
+          .GetWidgetCSSFrAttribute(
+            `${propPane._propertyControlSelectedColorButton("fillcolor")}`,
+            "background-color",
+          )
           .then((newColor) => {
             expect(sliderColor).to.eq(newColor);
           });

app/client/cypress/support/Pages/PropertyPane.ts

@@ -139,6 +139,8 @@ export class PropertyPane {
   _dropdownOptionSpan = ".t--dropdown-option span";
   public _propertyControlColorPicker = (property: string) =>
     `.t--property-control-${property} .bp3-input-group input`;
+  public _propertyControlSelectedColorButton = (property: string) =>
+    `.t--property-control-${property} ${this._fillColor}`;
   _propertyText = ".bp3-ui-text span";
   _paneTitle = ".t--property-pane-title";
   _segmentedControl = (value: string) =>