Update support template link in Manage:Import's escalation process

Why is this change being made?

As discussed in gitlab-com/support/support-team-meta#4543 (comment 1096269104), groupimport will be using a new support template when creating issues that require input from engineering. This MR updates the link in our escalation process handbook page to point to the new template.

/cc @jlyttle @m_frankiewicz

Author Checklist

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