[APM] Update Cypress command to access super date picker (elastic#191949

)

## 📓 Summary

Given a change in the HTML structure of the SuperDatePicker component
from EUI, the `selectAbsoluteTimeRange` was no longer capable of typing
the passed date.

Once the PR to update EUI was merged, it didn't go through the APM
Cypress suite since those files where not touched, causing the false
positive in the CI step.

This change directly accesses the input field without relying on sibling
elements.

Co-authored-by: Marco Antonio Ghiani <[email protected]>

x-pack/plugins/observability_solution/apm/ftr_e2e/cypress/support/commands.ts

@@ -88,18 +88,14 @@ Cypress.Commands.add('selectAbsoluteTimeRange', (start: string, end: string) =>
   const format = 'MMM D, YYYY @ HH:mm:ss.SSS';
 
   cy.getByTestSubj('superDatePickerstartDatePopoverButton').click();
-  cy.contains('Start date')
-    .nextAll()
-    .find('[data-test-subj="superDatePickerAbsoluteDateInput"]')
-    .clear({ force: true })
+  cy.getByTestSubj('superDatePickerAbsoluteDateInput').clear({ force: true });
+  cy.getByTestSubj('superDatePickerAbsoluteDateInput')
     .type(moment(start).format(format), { force: true })
     .type('{enter}');
 
   cy.getByTestSubj('superDatePickerendDatePopoverButton').click();
-  cy.contains('End date')
-    .nextAll()
-    .find('[data-test-subj="superDatePickerAbsoluteDateInput"]')
-    .clear({ force: true })
+  cy.getByTestSubj('superDatePickerAbsoluteDateInput').clear({ force: true });
+  cy.getByTestSubj('superDatePickerAbsoluteDateInput')
     .type(moment(end).format(format), { force: true })
     .type('{enter}');
 });