Remove fomantic segment module (#30042)

Another CSS-only module. Also, I re-ordered the imports based on
[original fomantic
order](https://github.com/fomantic/Fomantic-UI/blob/2.8.7/src/semantic.less).

web_src/css/base.css

@@ -360,6 +360,7 @@ ol.ui.list li,
 .ui.vertical.menu {
   background: var(--color-menu);
   border-color: var(--color-secondary);
+  box-shadow: none;
 }
 
 .ui.menu .item {
@@ -576,14 +577,6 @@ ol.ui.list li,
   visibility: visible !important;
 }
 
-.ui.error.segment {
-  border-color: var(--color-error-border) !important;
-}
-
-.ui.warning.segment {
-  border-color: var(--color-warning-border) !important;
-}
-
 .ui.selection.active.dropdown,
 .ui.selection.active.dropdown:hover,
 .ui.selection.active.dropdown .menu,
@@ -930,12 +923,6 @@ input:-webkit-autofill:active,
   background-color: transparent;
 }
 
-.ui.menu,
-.ui.vertical.menu,
-.ui.segment {
-  box-shadow: none;
-}
-
 /* replace fomantic popover box shadows */
 .ui.dropdown .menu,
 .ui.upward.dropdown > .menu,
@@ -1029,19 +1016,6 @@ input:-webkit-autofill:active,
   vertical-align: middle;
 }
 
-.ui .info.segment.top h3,
-.ui .info.segment.top h4 {
-  margin-top: 0;
-}
-
-.ui .info.segment.top h3:last-child {
-  margin-top: 4px;
-}
-
-.ui .info.segment.top > :last-child {
-  margin-bottom: 0;
-}
-
 .ui .form .autofill-dummy {
   position: absolute;
   width: 1px;
@@ -1678,23 +1652,6 @@ a.ui.basic.label:hover {
   margin-left: 0;
 }
 
-.ui.segment,
-.ui.segments,
-.ui.attached.segment {
-  background: var(--color-box-body);
-  color: var(--color-text);
-  border-color: var(--color-secondary);
-}
-
-.ui.segments > .segment {
-  border-color: var(--color-secondary);
-}
-
-.ui.secondary.segment {
-  background: var(--color-secondary-bg);
-  color: var(--color-text-light);
-}
-
 .rss-icon {
   display: inline-flex;
   color: var(--color-text-light-1);