chore: restructure test env, cassettes, and conftest; fix flaky tests

Consolidates pytest config, standardizes env handling, reorganizes cassette layout, removes outdated VCR configs, improves sync with threading.Condition, updates event-waiting logic, ensures cleanup, regenerates Gemini cassettes, and reverts unintended test changes.

lib/crewai/tests/cassettes/test_gemini_models[gemini-gemini-2.0-flash-001].yaml

@@ -1,33 +1,38 @@
 interactions:
 - request:
-    body: '{"contents": [{"role": "user", "parts": [{"text": "What is the capital
-      of France?"}]}], "generationConfig": {"stop_sequences": []}}'
+    body: '{"contents": [{"parts": [{"text": "What is the capital of France?"}], "role":
+      "user"}], "generationConfig": {}}'
     headers:
-      accept:
+      Accept:
       - '*/*'
-      accept-encoding:
-      - gzip, deflate
-      connection:
+      Accept-Encoding:
+      - gzip, deflate, zstd
+      Connection:
       - keep-alive
-      content-length:
-      - '131'
-      content-type:
+      Content-Length:
+      - '111'
+      Content-Type:
       - application/json
-      host:
-      - generativelanguage.googleapis.com
       user-agent:
-      - litellm/1.60.2
+      - google-genai-sdk/1.2.0 gl-python/3.12.9
+      x-goog-api-client:
+      - google-genai-sdk/1.2.0 gl-python/3.12.9
+      x-goog-api-key:
+      - X-GOOG-API-KEY-XXX
     method: POST
     uri: https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash-001:generateContent
   response:
     body:
-      string: !!binary |
-        H4sIAAAAAAAC/62RTU+EMBCG7/0VTY9kIQUT1vXqx0njRokxUQ8jDNAILaFdoyH8dwssbNGrTdo0
-        807nnT7TEUpZCjITGRjU7IK+2Ail3XgOmpIGpbHCHLLBBlpzyp1W59xtisGv4RFLSqQpNMJARVVO
-        b1qQKVKhqeftoRXa84JXyZy3/XJ/25wcW1XhUK5WGVZzej8nsFxIocsHBK3kkPaY3O/ZosJncauK
-        plXvQ9M+D3gUxiE/tzs6i+JtyHdkth5N2UFDgXdowFKB5e/Mlqgbk6gPlJfqMFLZTi4Ow5W8O8pG
-        WQArJYw3f4rqK2spKhetQ93+HSphvkes188Jc/iYVU8zH+Jg/N3hP3nt1l7kOJVpUE/YajFNpMDa
-        zsiPAu7nFejS5zxkpCc/6so6tIECAAA=
+      string: "{\n  \"candidates\": [\n    {\n      \"content\": {\n        \"parts\":
+        [\n          {\n            \"text\": \"The capital of France is **Paris**.\\n\"\n
+        \         }\n        ],\n        \"role\": \"model\"\n      },\n      \"finishReason\":
+        \"STOP\",\n      \"avgLogprobs\": -0.021610861023267109\n    }\n  ],\n  \"usageMetadata\":
+        {\n    \"promptTokenCount\": 7,\n    \"candidatesTokenCount\": 9,\n    \"totalTokenCount\":
+        16,\n    \"promptTokensDetails\": [\n      {\n        \"modality\": \"TEXT\",\n
+        \       \"tokenCount\": 7\n      }\n    ],\n    \"candidatesTokensDetails\":
+        [\n      {\n        \"modality\": \"TEXT\",\n        \"tokenCount\": 9\n      }\n
+        \   ]\n  },\n  \"modelVersion\": \"gemini-2.0-flash-001\",\n  \"responseId\":
+        \"wVIradyDDo_h_uMPlNSt4Qw\"\n}\n"
     headers:
       Alt-Svc:
       - h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
@@ -36,11 +41,11 @@ interactions:
       Content-Type:
       - application/json; charset=UTF-8
       Date:
-      - Tue, 22 Apr 2025 14:25:05 GMT
+      - Sat, 29 Nov 2025 20:08:33 GMT
       Server:
       - scaffolding on HTTPServer2
       Server-Timing:
-      - gfet4t7; dur=1219
+      - gfet4t7; dur=337
       Transfer-Encoding:
       - chunked
       Vary:
@@ -48,9 +53,9 @@ interactions:
       - X-Origin
       - Referer
       X-Content-Type-Options:
-      - nosniff
+      - X-CONTENT-TYPE-XXX
       X-Frame-Options:
-      - SAMEORIGIN
+      - X-FRAME-OPTIONS-XXX
       X-XSS-Protection:
       - '0'
     status: