[MD] Address UX comments

- Update data source column header in index pattern table
- Update index pattern column name to Title
- Remove data source search field error check given it is not required

Signed-off-by: Kristen Tian <tyarong@amazon.com>

CHANGELOG.md

@@ -24,6 +24,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * [Multi DataSource] Make text content dynamically translated & update unit tests ([#2570](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2570))
 * [Vis Builder] Change classname prefix wiz to vb ([#2581](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2581/files))
 * [Vis Builder] Change wizard to vis_builder in file names and paths ([#2587](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2587))
+* [Multi DataSource] Address UX comments on index pattern management stack ([#2611](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2611))
 
 ### 🐛 Bug Fixes
 * [Vis Builder] Fixes auto bounds for timeseries bar chart visualization ([2401](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2401))

src/plugins/data_source_management/public/components/data_source_column/data_source_column.tsx

@@ -24,7 +24,7 @@ export class DataSourceColumn implements IndexPatternTableColumn<DataSourceMap>
   public euiColumn = {
     field: 'referenceId',
     name: i18n.translate('dataSource.management.dataSourceColumn', {
-      defaultMessage: 'Data Source',
+      defaultMessage: 'Data source connection',
     }),
     render: (referenceId: string, index: IndexPatternTableRecord) => {
       if (!referenceId) {

src/plugins/index_pattern_management/public/components/create_index_pattern_wizard/components/step_data_source/components/header/header.tsx

@@ -160,7 +160,6 @@ export const Header: React.FC<HeaderProps> = (props: HeaderProps) => {
                     defaultMessage: 'Search data sources',
                   }
                 ),
-                isInvalid: !!dataSources,
               }}
               singleSelection={'always'}
               options={dataSources}

src/plugins/index_pattern_management/public/components/index_pattern_table/index_pattern_table.tsx

@@ -183,7 +183,7 @@ export const IndexPatternTable = ({ canSave, history }: Props) => {
   const columns = [
     {
       field: 'title',
-      name: 'Pattern',
+      name: 'Title',
       render: (
         name: string,
         index: {