[MD]Update test connection button text

CHANGELOG.md

@@ -91,6 +91,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [CI] Update test workflow to increase network-timeout for yarn for installing dependencies ([#3118](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3118))
 - [VisBuilder] Fixes pipeline aggs ([#3137](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3137))
 - [Region Maps] Fixes bug that prevents selected join field to be used ([#3213](Fix bug that prevents selected join field to be used))
+- [Multi DataSource]Update test connection button text([#3247](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3247))
 
 ### 🚞 Infrastructure
 

src/plugins/data_source_management/public/components/create_data_source_wizard/components/create_form/create_data_source_form.tsx

@@ -436,7 +436,7 @@ export class CreateDataSourceForm extends React.Component<
                 >
                   <FormattedMessage
                     id="dataSourcesManagement.createDataSource.testConnectionButton"
-                    defaultMessage="Test Connection"
+                    defaultMessage="Test connection"
                   />
                 </EuiButton>
               </EuiFlexItem>

src/plugins/data_source_management/public/components/edit_data_source/components/header/header.tsx

@@ -123,7 +123,7 @@ export const Header = ({
       >
         <FormattedMessage
           id="dataSourcesManagement.createDataSource.testConnectionButton"
-          defaultMessage="Test Connection"
+          defaultMessage="Test connection"
         />
       </EuiButton>
     );