Remove example and description from browser field (elastic#186897)

## Summary

Further progress towards cleaning up the sourcerer model, aligning it
with the FieldSpec. This PR removes description and examples fields from
the `BrowserField`, sourcing these from the EcsFlat available in
`@elastic/ecs` package.

x-pack/packages/security-solution/data_table/components/data_table/column_headers/helpers.test.tsx

@@ -228,10 +228,7 @@ describe('helpers', () => {
           aggregatable: true,
           columnHeaderType: 'not-filtered',
           defaultSortDirection,
-          description:
-            'Date/time when the event originated. For log events this is the date/time when the event was generated, and not when it was read. Required field for all events.',
           esTypes: ['date'],
-          example: '2016-05-23T08:05:34.853Z',
           format: '',
           id: '@timestamp',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
@@ -248,9 +245,7 @@ describe('helpers', () => {
           aggregatable: true,
           columnHeaderType: 'not-filtered',
           defaultSortDirection,
-          description: 'IP address of the source. Can be one or multiple IPv4 or IPv6 addresses.',
           esTypes: ['ip'],
-          example: '',
           format: '',
           id: 'source.ip',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
@@ -266,10 +261,7 @@ describe('helpers', () => {
           aggregatable: true,
           columnHeaderType: 'not-filtered',
           defaultSortDirection,
-          description:
-            'IP address of the destination. Can be one or multiple IPv4 or IPv6 addresses.',
           esTypes: ['ip'],
-          example: '',
           format: '',
           id: 'destination.ip',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
@@ -295,10 +287,7 @@ describe('helpers', () => {
           aggregatable: true,
           columnHeaderType: 'not-filtered',
           defaultSortDirection,
-          description:
-            'Date/time when the event originated. For log events this is the date/time when the event was generated, and not when it was read. Required field for all events.',
           esTypes: ['date'],
-          example: '2016-05-23T08:05:34.853Z',
           format: '',
           id: '@timestamp',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
@@ -351,9 +340,6 @@ describe('helpers', () => {
         const fieldName = 'test_field';
         const testField = {
           aggregatable: true,
-          description:
-            'Date/time when the event originated. For log events this is the date/time when the event was generated, and not when it was read. Required field for all events.',
-          example: '2016-05-23T08:05:34.853Z',
           format: 'date',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
           name: fieldName,
@@ -384,8 +370,6 @@ describe('helpers', () => {
         const fieldName = 'testFieldName';
         const testField = {
           aggregatable: true,
-          description: 'test field description',
-          example: '2016-05-23T08:05:34.853Z',
           format: 'date',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
           name: fieldName,
@@ -416,8 +400,6 @@ describe('helpers', () => {
         const fieldName = 'test.field.splittable';
         const testField = {
           aggregatable: true,
-          description: 'test field description',
-          example: '2016-05-23T08:05:34.853Z',
           format: 'date',
           indexes: ['auditbeat', 'filebeat', 'packetbeat'],
           name: fieldName,
@@ -448,9 +430,6 @@ describe('helpers', () => {
 
   describe('allowSorting', () => {
     const aggregatableField = {
-      description:
-        'The cloud account or organization id used to identify different entities in a multi-tenant environment. Examples: AWS account id, Google Cloud ORG Id, or other unique identifier.',
-      example: '666777888999',
       indexes: ['auditbeat', 'filebeat', 'packetbeat'],
       name: 'cloud.account.id',
       searchable: true,