Prevent concurrent database health checks from sharing a single connection

[TimHess]

Description

• Update RelationalDatabaseHealthContributor to take a connection factory so each health check manages its own connection, avoiding overlapping checks opening and closing the same connection at the same time.
• Pass the database type name directly to skip reflection.

Fixes #1732

Quality checklist

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[github-actions]

Summary - All Code Coverage (ubuntu-latest)

Assembly	Line coverage	Branch coverage
Steeltoe.Bootstrap.AutoConfiguration	97.4%	83.3%
Steeltoe.Common	86.4%	77%
Steeltoe.Common.Certificates	97.2%	80.2%
Steeltoe.Common.Hosting	83.5%	65%
Steeltoe.Common.Http	97.4%	80.9%
Steeltoe.Common.Logging	81.1%	56.2%
Steeltoe.Common.Net	64.5%	66.6%
Steeltoe.Configuration.Abstractions	96.3%	89.4%
Steeltoe.Configuration.CloudFoundry	98.4%	92.7%
Steeltoe.Configuration.ConfigServer	91.6%	86.2%
Steeltoe.Configuration.Encryption	97.6%	87.8%
Steeltoe.Configuration.Kubernetes.ServiceBindings	95.6%	82.6%
Steeltoe.Configuration.Placeholder	93.8%	82.6%
Steeltoe.Configuration.RandomValue	93.2%	83.3%
Steeltoe.Configuration.SpringBoot	98.3%	85%
Steeltoe.Connectors	94.4%	85.3%
Steeltoe.Connectors.EntityFrameworkCore	81%	65.3%
Steeltoe.Discovery.Configuration	96.3%	75%
Steeltoe.Discovery.Consul	91.5%	84%
Steeltoe.Discovery.Eureka	89.8%	80.6%
Steeltoe.Discovery.HttpClients	89.9%	91.4%
Steeltoe.Logging.Abstractions	99.4%	95.6%
Steeltoe.Logging.DynamicConsole	100%	92.3%
Steeltoe.Logging.DynamicSerilog	99.1%	95.4%
Steeltoe.Management.Abstractions	100%	100%
Steeltoe.Management.Endpoint	96%	87.1%
Steeltoe.Management.GitProperties.Build	95.1%	83.9%
Steeltoe.Management.Prometheus	95.8%	76.9%
Steeltoe.Management.Tasks	95.2%	80%
Steeltoe.Management.Tracing	100%	75%
Steeltoe.Security.Authentication.JwtBearer	100%	93.7%
Steeltoe.Security.Authentication.OpenIdConnect	87.7%	66.6%
Steeltoe.Security.Authorization.Certificate	95.6%	61.5%
Steeltoe.Security.DataProtection.Redis	100%	****

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[bart-vmware]

I think this test should be removed. It is highly complicated and basically proves nothing, because it is up to the code calling the constructor whether the DbConnection is shared or not.

[bart-vmware]

LGTM, except for the added test.

[bart-vmware]

This PR targets another PR. Please rebase on main, so it can be merged independently.