e2e vmcp tests are flaky

[yrobla]

Bug description

Tests fails repeatedly with:

VirtualMCPServer Inline Auth with Local Incoming when using local incoming with inline outgoing auth should proxy tool calls with inline auth configuration
/home/runner/work/toolhive/toolhive/test/e2e/thv-operator/virtualmcp/virtualmcp_inline_auth_test.go:162
  STEP: Creating MCP client with local auth @ 11/26/25 08:24:04.886
  STEP: Listing and calling backend tool through inline auth proxy @ 11/26/25 08:24:04.9
  Calling tool 'backend-fetch-inline-local_fetch' with local incoming and inline outgoing auth
  [FAILED] in [It] - /home/runner/work/toolhive/toolhive/test/e2e/thv-operator/virtualmcp/virtualmcp_inline_auth_test.go:208 @ 11/26/25 08:24:35.012
  STEP: Cleaning up test resources @ 11/26/25 08:24:35.012
• [FAILED] [30.139 seconds]
VirtualMCPServer Inline Auth with Local Incoming when using local incoming with inline outgoing auth [It] should proxy tool calls with inline auth configuration
/home/runner/work/toolhive/toolhive/test/e2e/thv-operator/virtualmcp/virtualmcp_inline_auth_test.go:162

  [FAILED] Tool call should succeed with inline auth
  Unexpected error:
      <*transport.Error | 0xc0002a42f0>: 
      transport error: failed to send request: failed to send request: Post "http://localhost:30018/mcp": EOF
      {
          Err: <*fmt.wrapError | 0xc0002221c0>{
              msg: "failed to send request: failed to send request: Post \"http://localhost:30018/mcp\": EOF",
              err: <*fmt.wrapError | 0xc000222180>{
                  msg: "failed to send request: Post \"http://localhost:30018/mcp\": EOF",
                  err: <*url.Error | 0xc0003f85d0>{
                      Op: "Post",
                      URL: "http://localhost:30018/mcp",
                      Err: <*errors.errorString | 0x2530cd0>{s: "EOF"},
                  },
              },
          },
      }
  occurred
  In [It] at: /home/runner/work/toolhive/toolhive/test/e2e/thv-operator/virtualmcp/virtualmcp_inline_auth_test.go:208 @ 11/26/25 08:24:35.012