test: try to make image test retryable

Use a unique filename so retries work on different files.

Uploading the existing file again would cause a conflict
resulting in retries failing.

Signed-off-by: Max <max@nextcloud.com>

cypress/e2e/images.spec.js

@@ -140,7 +140,6 @@ describe('Test all image insertion methods', () => {
 
 		// Upload test files to user's storage
 		cy.uploadFile('test.md', 'text/markdown')
-		cy.uploadFile('empty.md', 'text/markdown')
 		cy.uploadFile('github.png', 'image/png')
 
 		cy.nextcloudCreateUser(randUser2, 'password')
@@ -198,8 +197,10 @@ describe('Test all image insertion methods', () => {
 	})
 
 	it('Upload images with the same name', () => {
-		cy.uploadFile('empty.md', 'text/markdown')
-		cy.openFile('empty.md')
+		// make sure we start from an emtpy file even on retries
+		const filename = randHash() + '.md'
+		cy.uploadFile('empty.md', 'text/markdown', filename)
+		cy.openFile(filename)
 
 		const assertImage = index => {
 			return clickOnImageAction(ACTION_UPLOAD_LOCAL_FILE)