Run warmup phase and allow concurrency configuration

[thpierce]

In this commit we are enabling the warmup phase and allowing runs to have configurable concurrency. Also improved the commands provided in the README.

Testing:

OverheadTests > runAllTestConfigurations() > all-800-tps STANDARD_OUT
    ----------------------------------------------------------
     Run at Mon Mar 04 20:42:29 UTC 2024
     all-800-tps : Compares all DistroConfigs (800TPS test)
     100 users, 1s duration
    ----------------------------------------------------------
    DistroConfig                  :                      none     app_signals_disabled    app_signals_no_traces       app_signals_traces
    Run duration                  :                  00:00:13                 00:00:11                 00:00:13                 00:00:11
    Avg. CPU (user) %             :                       0.0                      0.0                      0.0                      0.0
    Max. CPU (user) %             :                       0.0                      0.0                      0.0                      0.0
    Avg. mch tot cpu %            :                       0.0                      0.0                      0.0                      0.0
    Startup time (ms)             :                      4010                     5013                     5014                     5013
    Total allocated MB            :                      0.00                     0.00                     0.00                     0.00
    Thread switch rate            :                       0.0                      0.0                      0.0                      0.0
    GC time (ms)                  :                         0                        0                        0                        0
    GC pause time (ms)            :                         0                        0                        0                        0
    Req. Count                    :                   1400.00                  1400.00                  1400.00                  1400.00
    Req. Rate                     :                    124.01                   144.99                   119.48                   146.53
    Req. Lat. mean (ms)           :                    481.05                   462.39                   509.49                   504.60
    Req. Lat. p0 (ms)             :                      2.06                     2.85                     2.08                     4.23
    Req. Lat. p50 (ms)            :                    159.19                   190.15                   175.91                   200.18
    Req. Lat. p90 (ms)            :                   1143.15                  1303.96                  1391.22                  1427.85
    Req. Lat. p99 (ms)            :                   5058.14                  3840.13                  4229.97                  4261.41
    Req. Lat. p100 (ms)           :                   8397.74                  5530.18                  8578.33                  5468.59
    Net read avg (bps)            :                      0.00                     0.00                     0.00                     0.00
    Net write avg (bps)           :                      0.00                     0.00                     0.00                     0.00
    Peak threads                  :                         0                        0                        0                        0

Gradle Test Executor 41 finished executing tests.

> Task :test
Finished generating test XML results (0.145 secs) into: /workplace/thp/python-sdk/aws-otel-python-instrumentation/performance-tests/build/test-results/test
Generating HTML test report...
Finished generating test html results (0.106 secs) into: /workplace/thp/python-sdk/aws-otel-python-instrumentation/performance-tests/build/reports/tests/test

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.6/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

BUILD SUCCESSFUL in 6m 49s
4 actionable tasks: 4 executed

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