Fix #10541 - Relation M2M between Security Groups and Security Groups raises an error

[SinergiaCRM]

Description

On class M2MRelationship, the function add has a special if when on side of the relationship is with Security Groups. When a relation between SGs and SGs is created, the execution flow follows this special IF, but that's wrong: normal flow should be followed.
This PR corrects the IF condition.

Motivation and Context

When a M2M relations between SGs and SGs exists, and anyone tries to select a SG from SG subpanel on SG detail view an error occurs.

How To Test This

1.Create a M2M relation between Security Groups and Security Groups
2.Create a new Security group
3.From the "Security Suite Management" subpanel select another existing security group

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Final checklist

• My code follows the code style of this project found here.
• My change requires a change to the documentation.
• I have read the How to Contribute guidelines.

[serhiisamko091184]

Hello @SinergiaCRM,

thanks for your contribution!

Regards,
Serhii