[IMP] theme_*: adapt themes tests for the new snippet category

*: artists, avantgarde, aviato, buzzy, orchid, paptic, real_estate,
treehouse, zap

This commit aims to adapt tests within each themes that uses the
`s_three_columns` snippet.

As we introduce the `Columns` category within the snippet modal, we are
moving the `s_three_columns` from the `Content` category to the `Columns`
one. This implies an adaptation of the tests where the `s_three_columns`
was defined as part of the `Content` category.

task-4119460
follow-up of task-3919405

closes odoo/design-themes#872

Related: odoo/odoo#176889
Signed-off-by: Robin Lejeune (role) <role@odoo.com>

theme_artists/static/src/js/tour.js

@@ -16,7 +16,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_title',

theme_avantgarde/static/src/js/tour.js

@@ -15,7 +15,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_text_image',

theme_aviato/static/src/js/tour.js

@@ -27,7 +27,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_picture',

theme_buzzy/static/src/js/tour.js

@@ -16,7 +16,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_image_text',

theme_orchid/static/src/js/tour.js

@@ -22,7 +22,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_quotes_carousel',

theme_paptic/static/src/js/tour.js

@@ -21,7 +21,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_comparisons',

theme_real_estate/static/src/js/tour.js

@@ -31,7 +31,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_title',

theme_treehouse/static/src/js/tour.js

@@ -21,7 +21,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_call_to_action',

theme_zap/static/src/js/tour.js

@@ -11,7 +11,7 @@ const snippets = [
     {
         id: 's_three_columns',
         name: 'Columns',
-        groupName: "Content",
+        groupName: "Columns",
     },
     {
         id: 's_color_blocks_2',