Fix ISM e2e tests for OS 2.7: conditional toast dismiss and failOnStatusCode

[aditi-1601]

Description

Fixes index-management-e2e (test_e2e_ism) failures on OS 2.7

• managed_indices_spec.js: replace unconditional toast dismiss calls with a
  conditional dismiss so the spec doesn't fail when no toast is present
• commands.js: deleteAllIndices now uses failOnStatusCode: false for robustness
  during cleanup

Issues Resolved

[List any issues this PR will resolve]

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
General	Avoid silently ignoring all request errors Setting failOnStatusCode: false unconditionally will silently swallow all errors, including real failures (e.g., auth or connection issues), which can mask problems. Consider narrowing this to acceptable status codes (like 404 when no indices exist) by checking the response status explicitly, or restore failure on unexpected codes. cypress/utils/commands.js [101-107] cy.request({ method: 'DELETE', url: `${Cypress.env( 'openSearchUrl' )}/index*,sample*,opensearch_dashboards*,test*,cypress*`, failOnStatusCode: false, + }).then((response) => { + if (response.status !== 200 && response.status !== 404) { + throw new Error(`Unexpected status deleting indices: ${response.status}`); + } }); Suggestion importance[1-10]: 5 __ Why: The suggestion raises a valid concern that failOnStatusCode: false can mask real errors, and narrowing acceptable status codes improves test reliability. However, the impact is moderate since this is test cleanup code.	Low