[lldb-dap] Fix URL label and error code in DAPError (#145010)

This patch fixes some problems in DAPerror class (unnecessary copy in
ctor and typo in getUrlLabel function). During patch testing I found
flaky test TestDAP_server.test_server_interrupt (at least 1 fail on 50
runs). Looks like this problem is caused by data race between main and
event handler threads. Terminated event can be sent from Disconnect
function and event handler. However, only event handler sends exit
event. Also, after disconnecting, socket will be closed, so sometimes
sending event fails with "write failed: transport IO object invalid"
error. I tried to fix this problem by adding a wait for events thread
after disconnecting.

Failed log example:
```log
1750366596.399511337 lldb-dap server shutdown requested, disconnecting remaining clients...
1750366596.406297684 (client_0) <-- 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1750366596.406688452 (client_0) write failed: transport IO object invalid
1750366596.406724215 (client_0) write failed: transport IO object invalid
1750366596.842197657 (client_0) client disconnected
```

0 files changed, 0 insertions, 0 deletions