refactor(core): move Bootstrap-related CSS to external

Declare styles for overriding Bootstrap defaults in
new external CSS file override_bootstrap.min.css instead
of in an internal stylesheet in a separate template (partial)
whose only purpose is to include styles.

apis_core/core/static/css/override_bootstrap.min.css

@@ -0,0 +1,6 @@
+/* override of Bootstrap 4.6.2 generated (min) version to partially
+fix an issue with select2
+TODO remove after move to Boostrap 5 */
+.select2-container--default .select2-selection span.select2-selection__rendered {
+    line-height: initial;
+}

apis_core/core/templates/base.html

@@ -52,6 +52,7 @@
       <link rel="stylesheet"
             href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.5/css/select2.min.css" />
       {% include "partials/bootstrap4_css.html" %}
+      <link href="{% static 'css/override_bootstrap.min.css' %}" rel="stylesheet" />
       <link href="{% static 'css/material-symbols.css' %}" rel="stylesheet" />
       <link href="{% static 'css/core.css' %}" rel="stylesheet" />
       <link href="{% static 'css/E53_Place_popover.css' %}" rel="stylesheet" />

apis_core/core/templates/partials/bootstrap4_css.html

@@ -3,9 +3,3 @@
       href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css"
       integrity="sha384-xOolHFLEh07PJGoPkLv1IbcEPTNtaed2xpHsD9ESMhqIYd0nLMwNLD69Npy4HI+N"
       crossorigin="anonymous">
-{# this is an override to partially fix an css issue with select2, shoule be removed when move to boostrap5 #}
-<style>
-     .select2-container--default .select2-selection span.select2-selection__rendered {
-        line-height: initial;
-      }
-</style>