[fix][trace] add per-space double-query whitelist for trajectory query

[whh935]

背景

线上 /open-api/observability/traces/trajectory 自 trajectory_metadata_config 打开全局 enable_single_query 后，对重 trace 大量返回 HTTP 200，但响应是空数据。single-query 路径一次 ListSpansRepeat 不设 SelectColumns（等价 SELECT *）、Limit 1000，单页体积易超 maxBytes（被吞成 200 空）或压垮 ClickHouse。

改动

给 TrajectoryMetadataConfig 增加 space 级白名单 enable_double_query_spaces：命中的 workspace_id 强制走 double-query 路径，即使全局 enable_single_query=true。用于对受影响 space 精准止血，同时不影响其他 space 的 single-query 行为。

• config.go：新增 EnableDoubleQuerySpaces []int64 字段 + nil-safe IsDoubleQueryEnabled(workspaceID)。字段缺失时为 nil slice，slices.Contains 返回 false，向前兼容。
• trace_service.go：GetTrajectories 分流改为 IsSingleQueryEnabled() && !IsDoubleQueryEnabled(workspaceID) 才走 single。
• 补充 TestTrajectoryMetadataConfig_IsDoubleQueryEnabled 单测。

配置用法

{
  "enable_single_query": true,
  "enable_double_query_spaces": [7578826558572331009]
}

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@           Coverage Diff           @@
##             main     #672   +/-   ##
=======================================
  Coverage   78.84%   78.84%           
=======================================
  Files         707      707           
  Lines       87896    87900    +4     
=======================================
+ Hits        69298    69308   +10     
+ Misses      14607    14604    -3     
+ Partials     3991     3988    -3     

Flag	Coverage Δ
unittests	78.84% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...es/observability/domain/component/config/config.go	58.33% <100.00%> (+5.20%)	⬆️
...bservability/domain/trace/service/trace_service.go	90.04% <100.00%> (ø)

... and 2 files with indirect coverage changes

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