Add index for UpdatedEntity field of ImportNotification

[tjpeel-ee]

The field is being used in PHA API queries. There are additional fields we are also filtering on so not sure if a composite index across all fields would be preferable?

For now, thought it made sense to at least include an index on UpdatedEntity.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Package	Line Rate	Branch Rate	Health
Btms.Business	82%	73%	✔
Btms.SyncJob	63%	45%	➖
Btms.Metrics	82%	0%	✔
Btms.Analytics	74%	73%	➖
Btms.Backend.Data	65%	60%	➖
Btms.Types.Ipaffs	95%	62%	✔
TestDataGenerator	83%	80%	✔
Btms.Backend	62%	39%	➖
Btms.BlobService	38%	27%	❌
Btms.Emf	11%	0%	❌
Btms.Common	72%	56%	➖
Btms.Azure	43%	100%	❌
Btms.Consumers	81%	72%	✔
Btms.Types.Alvs	85%	67%	✔
Btms.Types.Gvms.Mapping	38%	25%	❌
Btms.Types.Alvs.Mapping	81%	0%	✔
Btms.Types.Ipaffs.Mapping	77%	50%	➖
Btms.Types.Gvms	61%	100%	➖
Btms.SensitiveData	82%	89%	✔
Btms.Types.Alvs.Mapping.V1.Tests	0%	0%	❌
Btms.Model	93%	94%	✔
TestGenerator.IntegrationTesting.Backend	83%	71%	✔
Summary	78% (10111 / 12972)	62% (1024 / 1646)	➖