Remove GDK responsibilities from EP team handbook and role

Why is this change being made?

~"group::ecosystem" is now responsible for GDK after !37299 (merged)

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what