Revert "Revert "fdo#50183 Use one sheet as default in Calc""

This reverts commit 3e07bdfc.
The problems with the tests still assuming three sheets by default
have now been addressed.

officecfg/registry/schema/org/openoffice/Office/Calc.xcs

@@ -1649,7 +1649,7 @@
 				<author>Albert Thuswaldner</author>
 				<desc>Option to set initial number of sheet tabs</desc>
 			  </info>
-		  <value>3</value>
+		  <value>1</value>
 		</prop>
 		<prop oor:name="SheetPrefix" oor:type="xs:string">
 			  <!-- UIHints: Tools - Options - Spreadsheet - Defaults -->

sc/source/core/tool/defaultsoptions.cxx

@@ -61,7 +61,7 @@ ScDefaultsOptions::~ScDefaultsOptions()
 
 void ScDefaultsOptions::SetDefaults()
 {
-    nInitTabCount  = 3;
+    nInitTabCount  = 1;
     aInitTabPrefix = ScGlobal::GetRscString(STR_TABLE_DEF); // Default Prefix "Sheet"
 }