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: 306429419
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/BUILD b/src/main/java/com/google/devtools/build/lib/sandbox/BUILD
index b7cac33..dff9604 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/BUILD
@@ -37,6 +37,7 @@
         "//src/main/java/com/google/devtools/build/lib/vfs:pathfragment",
         "//src/main/java/com/google/devtools/common/options",
         "//third_party:auto_value",
+        "//third_party:flogger",
         "//third_party:gson",
         "//third_party:guava",
         "//third_party:jsr305",