Maintenance tasks for browser_ui/3_create/web_ide/web_terminal_spec.rb

The test browser_ui/3_create/web_ide/web_terminal_spec.rb has been in a quarantine for a while and got outdated to the point of offering insufficient coverage, the following needs to be addressed:

• Web Terminal for IDE feature was moved to Core in gitlab-org/gitlab#211685 (closed), we need to move/update the test and relevant page objects to reflect that - gitlab-org/gitlab!70337 (merged)
• Currently the test passes with a confirmed bug in place (false positive) - see gitlab-org/gitlab#338179 (comment 670627123). The test makes an assumption that the terminal started successfully based on a component appearing, not taking into account that it might display errors within. We need to verify the connection is successful in other way. MR: gitlab-org/gitlab!76277 (merged)