Clean up code in gr-apply-fix-dialog

When reading code, I found some unused code, not removed by
Change 350174 + I cleaned up some hard to read code.

Release-Notes: skip
Change-Id: I25c912ab5b5a6e73ae99035edbc961c609e03ad3
diff --git a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
index 7c224a9..a6a27c5 100644
--- a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
+++ b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
@@ -56,12 +56,6 @@
   @query('#applyFixDialog')
   applyFixDialog?: GrDialog;
 
-  /** The currently observed dialog by `dialogOberserver`. */
-  observedDialog?: GrDialog;
-
-  /** The current observer observing the `observedDialog`. */
-  dialogObserver?: ResizeObserver;
-
   @query('#nextFix')
   nextFix?: GrButton;
 
@@ -211,10 +205,6 @@
     `;
   }
 
-  override disconnectedCallback() {
-    super.disconnectedCallback();
-  }
-
   private renderHeader() {
     return html`
       <div slot="header">${this.currentFix?.description ?? ''}</div>
@@ -249,13 +239,21 @@
   private renderFooter() {
     const fixCount = this.fixSuggestions?.length ?? 0;
     const reasonForDisabledApplyButton = this.computeTooltip();
-    if (fixCount < 2 && !reasonForDisabledApplyButton) return nothing;
-    return html`<div slot="footer" class="fix-picker">
-      ${when(fixCount >= 2, () =>
-        this.renderNavForMultipleSuggestedFixes(fixCount)
-      )}
-      ${this.renderWarning(reasonForDisabledApplyButton)}
-    </div>`;
+    const shouldRenderNav = fixCount >= 2;
+    const shouldRenderWarning = !!reasonForDisabledApplyButton;
+
+    if (!shouldRenderNav && !shouldRenderWarning) return nothing;
+
+    return html`
+      <div slot="footer" class="fix-picker">
+        ${when(shouldRenderNav, () =>
+          this.renderNavForMultipleSuggestedFixes(fixCount)
+        )}
+        ${when(shouldRenderWarning, () =>
+          this.renderWarning(reasonForDisabledApplyButton)
+        )}
+      </div>
+    `;
   }
 
   private renderNavForMultipleSuggestedFixes(fixCount: number) {
@@ -406,9 +404,7 @@
   async handleApplyFix(e: Event) {
     if (e) e.stopPropagation();
 
-    const changeNum = this.changeNum;
-    const patchNum = this.patchNum;
-    const change = this.change;
+    const {changeNum, patchNum, change} = this;
     if (!changeNum || !patchNum || !change || !this.currentFix) {
       throw new Error('Not all required properties are set.');
     }