Check that files_external_ftp is working OK after Guzzle7 core update for core 10.11

[kiranadh1452]

Check the files_external_ftp with core 10.10 and make sure that any existing problems have issues.

Try again with current core master (to be 10.11 release), and raise issues for any new problems.

Related to issue https://github.com/owncloud/core/issues/39387

[kiranadh1452]

Except for the reported issues, following features work fine.

Core 10.10

• Mount External Storage Through FTP: :heavy_check_mark:
• View Files: :heavy_check_mark:
• Download Files: :heavy_check_mark:
• Delete Files: :heavy_check_mark:
• Upload Files: :heavy_check_mark:
• Federated Sharing of file: :heavy_check_mark:
• Federated Sharing of folder: :heavy_check_mark:

Core 10.11

• Mount External Storage Through FTP: :heavy_check_mark:
• View Files: :heavy_check_mark:
• Download Files: :heavy_check_mark:
• Delete Files: :heavy_check_mark:
• Upload Files: :heavy_check_mark:
• Federated Sharing of file: :heavy_check_mark:
• Federated Sharing of folder: :heavy_check_mark:

Some major issues found were: #93 #17

PS: These issues exist in 10.10 as well.