css: Remove unnecessary CSS for ".clear_search_button".

We can remove some of the CSS properties for
".clear_search_button" selectors because they
were being overridden by CSS set using more
specific selectors or by CSS set using
".bootstrap-btn" selector.

As a result, we can remove some the overriding
CSS as well where they were being used to set
default values.

web/styles/app_components.css

@@ -425,13 +425,9 @@ input.settings_text_input {
     &:focus,
     &:active,
     &:disabled:hover {
-        position: relative;
-        right: 20px;
         background: none;
         border: none;
         text-align: center;
-        padding-top: 8px;
-        padding-left: 4px;
         color: var(--color-text-clear-search-button);
         text-shadow: none;
         outline: none !important;

web/styles/popovers.css

@@ -641,8 +641,6 @@ ul.popover-group-menu-member-list {
         #clear_stream_search {
             display: none;
             grid-area: clear-search;
-            right: 0;
-            padding: 0;
         }
     }
 

web/styles/recent_view.css

@@ -160,7 +160,6 @@
 
     .clear_search_button {
         grid-area: clear-search;
-        right: 0;
         padding: 0;
     }
 

web/styles/subscriptions.css

@@ -545,7 +545,6 @@ h4.user_group_setting_subsection_title {
 #clear_search_stream_name,
 #clear_search_group_name {
     grid-area: clear-search;
-    right: 0;
     padding: 0;
 }