Remove border of slider rectangle in number line mode at position 0

docs/release-notes-editor.txt

 Editor
 ======
+1.25.0
+- Remove border of slider rectangle in number line mode at position 0
+
 1.24.0
 - Show arrow for slider in number line mode
 - Center the position of slider rectangle in number line mode

docs/release-notes-player.txt

 Player
 ======
+1.19.0
+- Remove border of slider rectangle in number line mode at position 0
+
 1.18.0
 - Show arrow for slider in number line mode
 - Center the position of slider rectangle in number line mode
@@ -12,7 +15,6 @@ Player
 - Use dot instead of comma as thousands separator in slider
 - Do not color the progress on the number line
 
-
 1.16.0
 - Start the valid value range for DropDown, Likert, RadioGroup, RadioGroupImages and ToggleButton at 1
   Attention! This can lead to incompatibilities when reloading units that were answered in IQB - TestCenter

projects/common/ui-elements/slider/slider.component.ts

@@ -102,7 +102,7 @@ import { FormElementComponent } from '../../directives/form-element-component.di
     // eslint-disable-next-line max-len
     '.arrow-head {width: 0; height: 0; border-top: 8px solid transparent; border-bottom: 8px solid transparent; border-left: 20px solid #555;}',
     // eslint-disable-next-line max-len
-    ':host ::ng-deep .bar-style .mat-slider-thumb {border-radius: 0; width: 9px; height: 40px; bottom: -20px; margin-right: 5px; background-color: #006064}',
+    ':host ::ng-deep .bar-style .mat-slider-thumb {border-radius: 0; border: none; width: 9px; height: 40px; bottom: -20px; margin-right: 5px; background-color: #006064}',
     ':host ::ng-deep .bar-style .mat-slider-track-fill {background-color: rgba(0,0,0,0);}',
     ':host ::ng-deep .bar-style .mat-slider-track-background {background-color: rgba(0,0,0,0);}'
   ]