Train analysis server with cfe too
Train analysis server with cfe too

Prior to this change the analysis server was trained in non-cfe mode
only, meaning that the playing field wasn't even.
This CL updates the training so both modes are trained, reducing the
cold server benchmark in cfe mode from ~76 to ~71 seconds on my machine.
This is still *way* more than the non-cfe version, but still.

Before:
```
$ out/ReleaseX64/dart pkg/analysis_server/benchmark/benchmarks.dart run analysis-server-cold
Running analysis-server-cold 3 times...
  {analysis-server-cold-analysis: {micros: 15779864}, analysis-server-cold-memory: {bytes: 254571344}}
  {analysis-server-cold-analysis: {micros: 15181035}, analysis-server-cold-memory: {bytes: 272837552}}
  {analysis-server-cold-analysis: {micros: 15029866}, analysis-server-cold-memory: {bytes: 312474240}}
Finished in 49 seconds.

{"benchmark":"analysis-server-cold","result":{"analysis-server-cold-analysis":{"micros":15029866},"analysis-server-cold-memory":{"bytes":254571344}}}


$ out/ReleaseX64/dart pkg/analysis_server/benchmark/benchmarks.dart run --use-cfe analysis-server-cold
Running analysis-server-cold 3 times...
  {analysis-server-cold-analysis: {micros: 76810701}, analysis-server-cold-memory: {bytes: 1634409696}}
  {analysis-server-cold-analysis: {micros: 74706698}, analysis-server-cold-memory: {bytes: 1565364624}}
  {analysis-server-cold-analysis: {micros: 75798888}, analysis-server-cold-memory: {bytes: 1759452128}}
Finished in 228 seconds.

{"benchmark":"analysis-server-cold","result":{"analysis-server-cold-analysis":{"micros":74706698},"analysis-server-cold-memory":{"bytes":1565364624}}}
```


Now:

```
$ out/ReleaseX64/dart pkg/analysis_server/benchmark/benchmarks.dart run analysis-server-cold
Running analysis-server-cold 3 times...
  {analysis-server-cold-analysis: {micros: 15064119}, analysis-server-cold-memory: {bytes: 302396944}}
  {analysis-server-cold-analysis: {micros: 14909304}, analysis-server-cold-memory: {bytes: 273778864}}
  {analysis-server-cold-analysis: {micros: 14934034}, analysis-server-cold-memory: {bytes: 353252928}}
Finished in 45 seconds.

{"benchmark":"analysis-server-cold","result":{"analysis-server-cold-analysis":{"micros":14909304},"analysis-server-cold-memory":{"bytes":273778864}}}



$ out/ReleaseX64/dart pkg/analysis_server/benchmark/benchmarks.dart run --use-cfe analysis-server-cold
Running analysis-server-cold 3 times...
  {analysis-server-cold-analysis: {micros: 70252048}, analysis-server-cold-memory: {bytes: 1650741520}}
  {analysis-server-cold-analysis: {micros: 70853869}, analysis-server-cold-memory: {bytes: 1579162320}}
  {analysis-server-cold-analysis: {micros: 71155850}, analysis-server-cold-memory: {bytes: 1579512288}}
Finished in 213 seconds.

{"benchmark":"analysis-server-cold","result":{"analysis-server-cold-analysis":{"micros":70252048},"analysis-server-cold-memory":{"bytes":1579162320}}}
```

Change-Id: I8fb75624c86605e7028a2b8483df85ebbd958b0d
Reviewed-on: https://dart-review.googlesource.com/70260
Reviewed-by: Devon Carew <e996497f4f2225f0ee7a9f4d1696ee710b488b66@google.com>
Reviewed-by: Kevin Millikin <a6737c91ef81c790d8ad0ae8762bd5b2332a6e42@google.com>
Commit-Queue: Jens Johansen <05223a3c6bdf76af6f84755eae231abeebcf4530@google.com>

dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk