`dotnetup` should handle transient network issue ` Error: nodename nor servname provided, or not known (builds.dotnet.microsoft.com:443)`

### Prerequisites

- [x] I have read the [dotnetup documentation](https://github.com/dotnet/sdk/tree/release/dnup/documentation/general/dotnetup).
- [x] I have searched for [existing dotnetup issues](https://github.com/dotnet/sdk/issues?q=is%3Aissue%20state%3Aopen%20label%3Adotnetup).
- [x] I have searched for [existing dotnetup discussions](https://github.com/dotnet/sdk/discussions/categories/dotnetup).

### Issue type

Bug report

### Description

Several tests all at once in a single CI run failed. https://dev.azure.com/dnceng-public/public/_build/results?buildId=1496107&view=logs&jobId=68f2ee65-ec18-580c-7ed2-d0a4cae11481&j=68f2ee65-ec18-580c-7ed2-d0a4cae11481&t=89557a5d-cf8b-5204-5db5-1c689223a1e8 This only occurred so far on the amd64 mac. It seems likely transient as the change for get-dotnetup scripts seems unrelated to this problem.

Many tests passed, so it also seems like a transient network problem that we should probably handle better.

```
total: 1094
failed: 7
succeeded: 1059
skipped: 28
duration: 5m 36s 735ms
```

```
failed RuntimeInstall ("9.0",Runtime) (134ms)
Test method Microsoft.DotNet.Tools.Dotnetup.Tests.InstallEndToEndTests.RuntimeInstall threw exception:
FluentAssertions.Execution.AssertionFailedException: Expected exitCode to be 0 because dotnetup exited with code 1. Output:
Error: nodename nor servname provided, or not known (builds.dotnet.microsoft.com:443)
, but found 1 (difference of 1).
at FluentAssertions.Execution.FallbackTestFramework.Throw(String message)
at FluentAssertions.Execution.DefaultAssertionStrategy.HandleFailure(String message)
at FluentAssertions.Execution.AssertionChain.FailWith(Func`1 getFailureReason)
at FluentAssertions.Numeric.NumericAssertionsBase`3.Be(T expected, String because, Object[] becauseArgs)
at Microsoft.DotNet.Tools.Dotnetup.Tests.InstallEndToEndTests.RuntimeInstall(String componentSpec, InstallComponent expectedComponent) in /Users/runner/work/1/s/test/dotnetup.Tests/DnupE2Etest.cs:123
at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
```

```
failed EnvScript_WorksWithSpecialCharactersInPath (133ms)
Test method Microsoft.DotNet.Tools.Dotnetup.Tests.InstallEndToEndTests.EnvScript_WorksWithSpecialCharactersInPath threw exception:
FluentAssertions.Execution.AssertionFailedException: Expected exitCode to be 0 because SDK installation failed with special characters in path. Output:
Error: nodename nor servname provided, or not known (builds.dotnet.microsoft.com:443)
, but found 1 (difference of 1).
at FluentAssertions.Execution.FallbackTestFramework.Throw(String message)
at FluentAssertions.Execution.DefaultAssertionStrategy.HandleFailure(String message)
at FluentAssertions.Execution.AssertionChain.FailWith(Func`1 getFailureReason)
at FluentAssertions.Numeric.NumericAssertionsBase`3.Be(T expected, String because, Object[] becauseArgs)
at Microsoft.DotNet.Tools.Dotnetup.Tests.InstallEndToEndTests.EnvScript_WorksWithSpecialCharactersInPath() in /Users/runner/work/1/s/test/dotnetup.Tests/DnupE2Etest.cs:144
at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
```

### dotnetup version

_No response_

Start with test/dotnetup.Tests/DnupE2Etest.cs, especially RuntimeInstall and EnvScript_WorksWithSpecialCharactersInPath, and review the linked CI failure. Trace the dotnetup installation path that produces the DNS error, then run the affected end-to-end tests; done means transient network failures are handled and these installation scenarios succeed.

Written by the indexing model from the issue text.