use static LanguageTag::convertTo...() instead of LanguageTag().get...()

They know best when a temporary LanguageTag instance is needed and when
not.

Change-Id: Ia0dc5b2d165b15362080d60dbb9f58cfa0403014
diff --git a/linguistic/source/lngsvcmgr.cxx b/linguistic/source/lngsvcmgr.cxx
index 3f5dbff..10a1eeb 100644
--- a/linguistic/source/lngsvcmgr.cxx
+++ b/linguistic/source/lngsvcmgr.cxx
@@ -715,7 +715,7 @@ void LngSvcMgr::UpdateAll()
        const OUString *pNodeName = aNodeNames.getConstArray();
        for (i = 0;  i < nNodeNames;  ++i)
        {
            Locale aLocale( (LanguageTag(pNodeName[i])).getLocale() );
            Locale aLocale( LanguageTag::convertToLocale( pNodeName[i]));
            Sequence< OUString > aCfgSvcs( getConfiguredServices( aService, aLocale ));
            Sequence< OUString > aAvailSvcs( getAvailableServices( aService, aLocale ));

@@ -734,7 +734,7 @@ void LngSvcMgr::UpdateAll()
        const Locale *pAvailLocale = aAvailLocales.getConstArray();
        for (i = 0;  i < nAvailLocales;  ++i)
        {
            OUString aCfgLocaleStr( (LanguageTag(pAvailLocale[i])).getBcp47() );
            OUString aCfgLocaleStr( LanguageTag::convertToBcp47( pAvailLocale[i]));

            Sequence< OUString > aAvailSvcs( getAvailableServices( aService, pAvailLocale[i] ));

@@ -1777,7 +1777,7 @@ bool LngSvcMgr::SaveCfgSvcs( const OUString &rServiceName )
            aCfgAny <<= aSvcImplNames;
            DBG_ASSERT( aCfgAny.hasValue(), "missing value for 'Any' type" );

            OUString aCfgLocaleStr( (LanguageTag(pLocale[i])).getBcp47() );
            OUString aCfgLocaleStr( LanguageTag::convertToBcp47( pLocale[i]));
            pValue->Value = aCfgAny;
            pValue->Name  = aNodeName + "/" + aCfgLocaleStr;
            pValue++;