Closes #14871: Complete work on UI cleanup (#15341)

* Fix left padding of login button in top menu

* Relocate "add" buttons for embedded object tables

* Remove unused data template block & getNetboxData() utility function

* Remove bottom margin from last <p> element in rendered Markdown inside a table cell

* Prevent TomSelect from initializing on <select> elements with a size

* Fix styling of dropdown menu button for circuit commit rate

* Change .color-block to display: inline-block

* Delete unused static asset

* Improve contrast between menu group headings & items

* Remove custom color for attr-table row headings

* Fix border color of copy-to-clipboard button

* Fix toast text color in dark mode

* Fix rack elevation label/image toggles

* Increase border radius for small buttons

* Fix object selector

netbox/project-static/styles/custom/_markdown.scss

@@ -28,6 +28,13 @@
 
 }
 
+// Remove the bottom margin of <p> elements inside a table cell
+td > .rendered-markdown {
+  p:last-of-type {
+    margin-bottom: 0;
+  }
+}
+
 // Markdown preview
 .markdown-widget {
   .preview {

netbox/project-static/styles/custom/_misc.scss

@@ -2,7 +2,7 @@
 
 // Color labels
 span.color-label {
-  display: block;
+  display: inline-block;
   width: 5rem;
   height: 1rem;
   padding: $badge-padding-y $badge-padding-x;

netbox/project-static/styles/overrides/_tabler.scss

@@ -9,6 +9,10 @@ pre {
   // Tabler sets display: flex
   display: inline-block;
 }
+.btn-sm {
+  // $border-radius-sm (2px) is too small
+  border-radius: $border-radius;
+}
 
 // Tabs
 .nav-tabs {

netbox/project-static/styles/transitional/_tables.scss

@@ -23,7 +23,6 @@ table.attr-table {
 
   // Restyle row header
   th {
-    color: $gray-700;
     font-weight: normal;
     width: min-content;
   }