Linked Time: Removed old customVisTemplate that is no longer used (#5912)

* Motivation for features / changes
The new implementation of Linked time moved away from this template but
it has not been removed. This PR has no visible change in UI or features
but removes a lot of unused code.

* Technical description of changes
We have now switched over to using the lineChartCustomXAxisVis for all
linked time needs.

Author: JamesHollyer

tensorboard/webapp/metrics/views/card_renderer/scalar_card_component.ng.html

@@ -113,7 +113,6 @@
     [useDarkMode]="useDarkMode"
     (onViewBoxOverridden)="isViewBoxOverridden = $event"
     (viewBoxChanged)="onLineChartZoom.emit($event)"
-    [customVisTemplate]="lineChartCustomVis"
     [customChartOverlayTemplate]="lineChartCustomXAxisVis"
   ></line-chart>
   <ng-template
@@ -182,45 +181,6 @@
     </scalar-card-data-table>
   </div>
 </ng-container>
-<ng-template
-  #lineChartCustomVis
-  let-viewExtent="viewExtent"
-  let-domDim="domDimension"
-  let-xScale="xScale"
->
-  <ng-container *ngIf="stepOrLinkedTimeSelection">
-    <div
-      [ngClass]="{
-        'out-of-selected-time': true,
-        start: true,
-        range: !!stepOrLinkedTimeSelection.end?.step
-      }"
-      [style.right]="
-        xScale.forward(
-          viewExtent.x,
-          [domDim.width, 0],
-          stepOrLinkedTimeSelection.start.step
-        ) + 'px'
-      "
-    ></div>
-    <div
-      *ngIf="stepOrLinkedTimeSelection.end?.step"
-      [ngClass]="{
-        'out-of-selected-time': true,
-        end: true,
-        range: true
-      }"
-      [style.left]="
-        xScale.forward(
-          viewExtent.x,
-          [0, domDim.width],
-          stepOrLinkedTimeSelection.end?.step
-        ) + 'px'
-      "
-    ></div>
-  </ng-container>
-</ng-template>
-
 <ng-template
   #lineChartCustomXAxisVis
   let-viewExtent="viewExtent"

tensorboard/webapp/widgets/line_chart_v2/line_chart_component.ng.html

@@ -53,17 +53,6 @@
       (onViewExtentChange)="onViewBoxChanged($event)"
       (onViewExtentReset)="viewBoxReset()"
     ></line-chart-interactive-view>
-    <div *ngIf="customVisTemplate" class="custom-vis">
-      <ng-container
-        [ngTemplateOutlet]="customVisTemplate"
-        [ngTemplateOutletContext]="{
-          xScale: xScale,
-          yScale: yScale,
-          domDimension: domDimensions.main,
-          viewExtent: viewBox
-        }"
-      ></ng-container>
-    </div>
   </div>
   <div class="y-axis" #yAxis>
     <line-chart-axis

tensorboard/webapp/widgets/line_chart_v2/line_chart_component.ts

@@ -91,14 +91,6 @@ export class LineChartComponent
   @ViewChild('chartEl', {static: false, read: ElementRef})
   private chartEl?: ElementRef<HTMLCanvasElement | SVGElement>;
 
-  /**
-   * Optional ngTemplate that renders on top of line chart (not axis). This
-   * template is rendered on top of interactive layer and can mask other
-   * contents. Do note that this component may not intercept pointer-events.
-   */
-  @Input()
-  customVisTemplate?: TemplateRef<TemplateContext>;
-
   @Input()
   customChartOverlayTemplate?: TemplateRef<
     TemplateContext & {formatter: Formatter}