ATLAS-5156: Import failure due to missing support for handling multip…

[sheetalshah1007]

…le relationship types under a single attribute

What changes were proposed in this pull request?

Multiple relationship types handling in EntityGraphMapper is refactored so that a single relationship attribute (like hive_db.tables) can safely support multiple relationshipDefs (e.g. hive_table_db, delta_table_db), choosing the appropriate relationship type per element instead of once for the whole attribute.

• The collection case now:
  Groups related objects by their compatible relationship type via groupElementsByRelationshipType.
  Maps each group with the correct AtlasAttribute, logging and ignoring elements whose type doesn’t match any relationshipDef

• The single-element case now:
  Tries to find an appropriate relationship type; if none is found (e.g. Glossary term, invalid type), it logs and skips that value instead of failing or risking NPEs, preserving backward compatibility`.

How was this patch tested?

A dedicated test class, EntityGraphMapperMultipleRelationshipTypesTest, is introduced to:

• Verify mixed hive_table/delta_table collections are correctly split and mapped.
• Ensure the right relationshipDefs are used.
• Confirm invalid element types are ignored and do not create relationships.