Bug: Log Client fails are not handled or retried

[thantos]

https://github.com/functionless/eventual/actions/runs/3940856564/jobs/6743496373

Log failures can cause the orchestrator to fail.

{
    "errorType": "Runtime.UnhandledPromiseRejection",
    "errorMessage": "Error: Logs failed to send",
    "reason": {
        "errorType": "Error",
        "errorMessage": "Logs failed to send",
        "stack": [
            "Error: Logs failed to send",
            "    at LogAgent.flush (/packages/@eventual/core/src/runtime/log-agent.ts:222:15)",
            "    at processTicksAndRejections (node:internal/process/task_queues:96:5)",
            "    at null.timed (/packages/@eventual/core/src/runtime/metrics/utils.ts:11:18)"
        ]
    },
    "promise": {},
    "stack": [
        "Runtime.UnhandledPromiseRejection: Error: Logs failed to send",
        "    at process.<anonymous> (file:///var/runtime/index.mjs:1194:17)",
        "    at process.emit (node:events:527:28)",
        "    at emit (node:internal/process/promises:140:20)",
        "    at processPromiseRejections (node:internal/process/promises:274:27)",
        "    at processTicksAndRejections (node:internal/process/task_queues:97:32)"
    ]
}