Clean up layout-files

- Change text to symbols
- Remove unused button-definitions

This makes these layout-files easier to understand and edit.

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/629>

data/keyboards/ru.yaml

@@ -13,7 +13,7 @@ views:
         - "й ц у к е н г ш щ з х"
         - "ф ы в а п р о л д ж э"
         - "Shift_L  я ч с м и т ь б ю  BackSpace"
-        - "show_numbers preferences    ё  space  ъ  period Return"
+        - "show_numbers preferences    ё  space  ъ  . Return"
     upper:
         - "Й Ц У К Е Н Г Ш Щ З Х"
         - "Ф Ы В А П Р О Л Д Ж Э"
@@ -22,13 +22,13 @@ views:
     numbers:
         - "1 2 3 4 5 6 7 8 9 0"
         - "@ # $ % & - _ + ( )"
-        - "show_symbols   , \" ' colon ; ! ?  BackSpace"
-        - "show_letters preferences         space_fill   period Return"
+        - "show_symbols   , \" ' : ; ! ?  BackSpace"
+        - "show_letters preferences         space_fill   . Return"
     symbols:
         - "~ ` | · √ π τ ÷ × ¶"
         - "© ® £ € ¥ ^ ° * { }"
         - "show_numbers_from_symbols   \\ / < > = [ ]  BackSpace"
-        - "show_letters preferences         space_fill   period Return"
+        - "show_letters preferences         space_fill   . Return"
 
 buttons:
     Shift_L:
@@ -66,9 +66,8 @@ buttons:
             set_view: "symbols"
         outline: "wide"
         label: "*/="
-    period:
+    .:
         outline: "special"
-        text: "."
     comma:
         outline: "special"
         text: ","
@@ -82,8 +81,6 @@ buttons:
         outline: "wide"
         icon: "key-enter"
         keysym: "Return"
-    colon:
-        text: ":"
     ё:
         outline: "narrow"
     Ё: