The exception may be thrown before LOG is initialized.
Such as wrong config value. So we need to print it to fe.out, otherwise
we can't know what's wrong.
After this PR, the error can be found in fe.out, such as:
```
java.lang.NumberFormatException: For input string: "3g"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Long.parseLong(Long.java:589)
at java.lang.Long.parseLong(Long.java:631)
at org.apache.doris.common.ConfigBase.setConfigField(ConfigBase.java:253)
at org.apache.doris.common.ConfigBase.setFields(ConfigBase.java:232)
at org.apache.doris.common.ConfigBase.initConf(ConfigBase.java:146)
at org.apache.doris.common.ConfigBase.init(ConfigBase.java:112)
at org.apache.doris.DorisFE.start(DorisFE.java:101)
at org.apache.doris.DorisFE.main(DorisFE.java:73)
```