Let `/page` quick action to support case-insensitive escalation policy names

What does this MR do and why?

This MR enables the /page quick action to accept case-insensitive escalation policy names.

Related to #352804 (closed)

database Query plan

SELECT "incident_management_escalation_policies".* FROM "incident_management_escalation_policies" WHERE "incident_management_escalation_policies"."project_id" = 14986497 AND (LOWER(name) = LOWER('oN-cAlL EsCaLation poLicY'))

 Index Scan using index_on_project_id_escalation_policy_name_unique on public.incident_management_escalation_policies  (cost=0.27..3.29 rows=1 width=61) (actual time=3.211..3.213 rows=1 loops=1)
   Index Cond: (incident_management_escalation_policies.project_id = 14986497)
   Filter: (lower(incident_management_escalation_policies.name) = 'on-call escalation policy'::text)
   Rows Removed by Filter: 0
   Buffers: shared hit=3 read=3 dirtied=1
   I/O Timings: read=3.164 write=0.000

See https://console.postgres.ai/shared/bb1443d4-f2d1-4083-9974-c65d37131681

Screenshots or screen recordings

/page case-insensitive

How to set up and validate locally

1. Enable GitLab Ultimate
2. Create escalation policy
3. Create incident
4. Use page <mixed case policy name>

MR acceptance checklist

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