Migrating to fluent logging (green).

I did some minor clean-ups of the resulting logging statements (mostly moving/adding exceptions as causes that were missed), and a few other drive-bys.

PiperOrigin-RevId: 306265560
diff --git a/src/main/java/com/google/devtools/build/lib/concurrent/BUILD b/src/main/java/com/google/devtools/build/lib/concurrent/BUILD
index 21a940a..b370069 100644
--- a/src/main/java/com/google/devtools/build/lib/concurrent/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/concurrent/BUILD
@@ -13,6 +13,7 @@
     name = "concurrent",
     srcs = glob(["*.java"]),
     deps = [
+        "//third_party:flogger",
         "//third_party:guava",
         "//third_party:jsr305",
     ],