Spring Remove APIs deprecated for removal in 6.1

Remove APIs that have been "deprecated for removal in 6.1".

Candidates

• [x] methods in org.springframework.util.Assert
• [x] org.springframework.core.task.support.ConcurrentExecutorAdapter
• [x] org.springframework.test.web.reactive.server.ExchangeResult.getRawStatusCode()
• [x] org.springframework.http.HttpMethod.resolve(String)
• [x] org.springframework.http.HttpRequest.getMethodValue()
• [x] org.springframework.http.client.HttpComponentsClientHttpRequestFactory.setReadTimeout(int)
• [x] org.springframework.http.client.reactive.ClientHttpResponse.getRawStatusCode()
• [x] methods in org.springframework.jdbc.datasource.init.ScriptUtils
• [x] constructors in org.springframework.web.HttpRequestMethodNotSupportedException
• [x] org.springframework.web.reactive.function.client.ClientResponse.rawStatusCode()

Comment From: sbrannen

I made an initial pass to remove deprecated APIs in af170f693a921f1d4e79205cdf49e2644f12ddaa and 7df2e2a8d2a845984cde806232181da486dcf7bd.

The team will make an additional pass in conjunction with #30604.

In light of that, I am closing this issue.